Download Epidermal growth factor receptor mutations in lung

Pathology International 2007; 57: 233–244
doi:10.1111/j.1440-1827.2007.02098.x
Review Article
Epidermal growth factor receptor mutations in lung cancers
Yasushi Yatabe1 and Tetsuya Mitsudomi2
Departments of 1Pathology and Molecular Diagnostics and 2Thoracic Surgery, Aichi Cancer Center, Nagoya, Japan
In 2004, two groups reported somatic mutations in the
gene for the epidermal growth factor receptor (EGFR) in
patients with non-small cell lung cancer (NSCLC), which
were highly correlated with the clinical response to the
anticancer drug, gefitinib. Since then, a tremendous
amount of knowledge has accumulated, and sheds light on
significant oncological properties as well as the clinical
relevance of this mutation, which could be applicable to
other malignancies. The EGFR mutations are distributed
throughout the kinase domain, but a deletion in exon 19
and the point mutation L858R in exon 21 account for
approximately 90%, which confer a greater response to
gefitinib treatment, compared with other types of EGFR
mutations. These EGFR mutations in the tyrosine kinase
domain are seldom acquired in cancers of the other
organs and the mutations preferentially involve a subset
of lung cancers, which are clinicopathologically characterized by female sex, non-smoking, adenocarcinoma
histology and East Asian ethnicity. In Japan, the EGFR
mutations are detected in approximately 30% of overall
NSCLC and approximately 40% of surgically resected
adenocarcinomas. The morphological features of adenocarcinomas harboring the mutations were reported to be
frequent in those with bronchioloalveolar features, but it is
suggested that the cellular lineage of the putative original
cells of the cancers refines the subset more clearly. In the
present study the current knowledge of EGFR mutations is
reviewed, insights from which raise many further questions, and thus suggest new directions for future research.
sent 80% of lung cancers and surgery is the most efficient
curative treatment. However, patients at an operable stage
account for only 20% of them. For advanced NSCLC,
platinum-based chemotherapy as a standard treatment
achieves at best partial response in only approximately 30%
of patients and a modest increase in survival.2,3 The survival
rate at 1 year after first-line chemotherapy is around 30–40%
with 8–10 months median survival.4 These treatments are
associated with considerable toxicity, particularly myelosuppression, and thus more effective and less toxic treatments
are clearly needed for advanced NSCLC.
To address this problem, a new class of drugs that specifically targets certain molecular pathways has been developed. Epidermal growth factor receptor (EGFR) is one of
such targets, because the EGFR is frequently overexpressed
and aberrantly activated in NSCLC.5 Gefitinib (Iressa; AstraZeneca, Tokyo, Japan) and erlotinib (Tarceva; Roche, Tokyo,
Japan) are a selective tyrosine kinase inhibitor (TKI) of EGFR
that binds to the ATP-binding pocket of the EGFR kinase
domain and blocks downstream signaling.6,7 This agent was
first licensed in Japan, so Japanese clinicians were the first to
encounter the severe side-effect of interstitial pneumonitis,
which is occasionally lethal.
Key words: epidermal growth factor receptor, lung cancers,
molecular classification, non-smoker, oncogene addiction
Enigmas in gefitinib response
Each year, approximately 1.2 million new cases of lung
cancer are diagnosed worldwide, and 1.1 million patients die
of the disease.1 Non-small cell lung cancers (NSCLC) repreCorrespondence: Yasushi Yatabe, MD, Department of Pathology and
Molecular Diagnostics, Aichi Cancer Center Hospital, Kanokoden,
Chikusa-ku, Nagoya 464-8681, Japan. Email: [email protected]
Received 9 January 2007. Accepted for publication 18 January
2007.
© 2007 The Authors
Journal compilation © 2007 Japanese Society of Pathology
MUTATION OF THE EGFR TYROSINE KINASE DOMAIN
Despite its side-effects, gefitinib has had a major impact on
the treatment of advanced NSCLC, because the response
can be very dramatic even within a short period of administration, as shown in Fig. 1. However, this remarkable
response is limited to a subset of patients. Detailed analysis
of phase II trials of gefitinib, IDEAL 1 and 2, found that such
a high response can be found most frequently in women
and among those who have never smoked, patients with
adenocarcinomas, and ethnic Japanese.9,10 The lung
cancers seen in this subset of patients are far different from
those in which EGFR is highly expressed, and such a high
234
Y. Yatabe and T. Mitsudomi
(a)
(c)
(b)
Figure 1 Representative case of a gefitinib responder. An 80-year-old man could not drink a cup of water because of (a) massive pleural
effusion and lymph node metastasis around the esophagus 1 year after pulmonary resection for lung adenocarcinoma. A small tumor tissue
was obtained by endoscopic ultrasound fine-needle cytology, and (c) subsequent molecular analysis indicated positive epidermal growth factor
receptor mutation (L858R). Methodological details have been described elsewhere.8 (b) At 3 months after start gefitinib therapy, the tumor
regressed dramatically. The patient was discharged from the hospital on foot, 6 months after initiation of gefitinib treatment. Because he was
a smoker, gefitinib treatment would not have been chosen without this molecular diagnosis.
level of EGFR expression is seen mostly in squamous cell
carcinoma (50%-80%),5,11 which are more frequent among
smokers and male patients. Indeed, in the trial, there were no
consistent associations between EGFR expression levels
and gefitinib response.10 The reason for this remained unclear for a while.
Discovery of EGFR mutations
In 2004, two groups reported somatic mutations in the EGFR
gene in NSCLC, which were highly correlated with the gefitinib response.12,13 Soon after, a similar finding was confirmed
for erlotinib, another low-molecular-weight EGFR-TKI.14 So
far, a large amount of data on EGFR mutations in lung
cancers has now accumulated. All relevant mutations involve
the ATP-binding pocket of the receptor’s tyrosine kinase
Figure 2 Types and frequencies of epidermal growth factor receptor mutation. Three different types of mutation are acquired, including
in-frame deletions, in-frame insertion/duplications and point mutations. Deletions in exon 19 and a point mutation of L858R constitute
around 90% of all the mutations. Other alterations, mostly point
mutations, are scattered in the kinase domain and those are not
shown in this figure. These mutations, except for insertion/
duplications in exon 20 and T790M, generally increase in response
to gefitinib treatment, but the magnitude varies.
© 2007 The Authors
Journal compilation © 2007 Japanese Society of Pathology
EGFR mutations in lung cancers
domain, the target of these agents. The mutations confer a
selective growth advantage for affected lung cells. The high
susceptibility to gefitinib treatment among EGFR-mutated
lung cancers indicates that such mutations play a fundamental biological role in oncogenesis because the maintenance
of the malignant phenotype appears to be highly dependent
on the mutations; it has been likened to ‘addiction to the
mutated oncogene’.15
Biological characteristics of EGFR gene mutation
The EGFR mutations distributed throughout this region
(Fig. 2) consist of in-frame deletions, in-frame insertions/
duplications and point mutations.12–14,16–25 Among these alterations, an in-frame deletion in exon 19 and the point mutation
L858R in exon 21 account for approximately 90% and are
termed ‘classical’ mutations. According to the mutation site
and pattern, the tumorigenicity and response to TKI differed
on in vitro analysis.26 Compared with the G719S mutation
and insertions in exon 20, the classical mutations confer a
higher capacity for tumor formation and a greater response to
TKI treatment. Even among the classical mutations, the deletion in exon 19 confers higher malignant transformability than
the L858R point mutation. Indeed, this difference may reflect
patient survival.27,28
Recently, gene-targeted mice have been generated in
which mutant EGFR genes are expressed specifically
in pneumocytes.29,30 The mice develop adenocarcinomas
resembling human bronchioloalveolar carcinomas (BAC) and
its invasive forms. These tumors are highly sensitive to lowmolecular-weight compounds of EGFR-TKI and humanized
anti-EGFR antibody (cetuximab) treatments, similar to observations among lung cancer patients. Of note, withdrawal of
mutant EGFR molecules after complete development of lung
adenocarcinomas led to their marked regression, suggesting
that maintenance of these lung tumors is highly dependent
on continued expression of the mutants. This mouse model
will facilitate further understanding of the pharmacological
mechanisms involved and will help us discover ways to overcome drug resistance.31
EGFR gene amplification
EGFR gene amplification has been reported in glioblastomas, head and neck cancers, breast cancers, and
others.32–35 Lung cancers also harbor gene amplifications,
which have been reported in association with the response
to EGFR-TKI treatment. A group from Colorado University
reported that abnormal fluorescence in situ hybridization
© 2007 The Authors
Journal compilation © 2007 Japanese Society of Pathology
235
(FISH) findings rather than mutation were a better predictor
for the outcome of EGFR-TKI treatment, although high polyploidy in addition to gene amplification was included as a
FISH-positive category.22,36,37 However, quantitative polymerase chain reaction (PCR) did not confirm this, probably
because histological subtypes other than adenocarcinomas
with gene amplification may be overrepresented, and its
biological significance may differ from that with regard to
adenocarcinomas.23
Although the clinical response of EGFR-TKI for treating
lung cancers with and without the presence of gene amplification remains controversial,20,37 lung adenocarcinomas
with gene amplification constitute a subset of those with
gene mutations. Takano et al. examined 66 NSCLC, 13
(20%) of which harbored sixfold increased copy number
and all of these were EGFR-mutated cancers.25 Similar
findings were obtained by other groups as well as our
own.20,23,38 We speculated that EGFR gene amplification
functions as a secondary hit, like simultaneous mutations
of p53 and EGFR genes.39 Further detailed analysis is
warranted.
Secondary mutations causing acquired resistance to
gefitinib treatment
Patients with EGFR-mutated lung cancers who initially
achieve a marked response to EGFR-TKI treatment eventually develop progression of the disease during the course.
This acquired resistance is caused by a secondary mutation
at least in part, which is well known in causing imatinib
resistance for patients with chronic myelogenous leukemia.40,41 Currently, the T790M mutation, in addition to the
primary mutation of the EGFR gene, is frequently detected in
treatment-refractory cancers.42,43 In our analysis, half of the
patients with acquired resistance harbored this secondary
mutation.44 Figure 3 shows a representative case.
It is of note that despite its rarity, the T790M point mutation independent of gefitinib treatment is also seen in
primary lung cancers. Toyooka et al. reported two of 397
primary resected lung cancers that harbored simultaneous
T790M and L858R mutations, nevertheless neither chemotherapy nor irradiation was applied. A recurrent tumor in
one of the patients did not respond to gefitinib.45 Similar
simultaneous mutations have been also reported in the lung
cancers that developed in a hereditary fashion.46 Detailed
analysis showed that affected family members had germline
mutation of T790M, and that the lung cancers developed in
the family members acquired somatic mutations, such as
L858R and deletion in exon 19, in addition to the germline
T790M mutation. Notably, the somatic mutations were
acquired in cis to germline T790M mutation in these cases.
236
a
Y. Yatabe and T. Mitsudomi
b
c
d
(e)
(f)
Figure 3 Acquired secondary mutation. A 78-year-old woman was initially treated with gefitinib for lung adenocarcinoma with metastasis to
mediastinal lymph nodes. Significant regression of the cancers both in the lung and in metastatic lymph nodes was achieved by the treatment.
Two months later, the tumor regrew but only in the lung. Standard lobectomy with lymph node dissection was undertaken. To examine
mutational status, we isolated cancer cells from four lesions including (a,b) two portions within the main tumors and one metastatic cancer each
in the (c) para-aortic and (d) lobar lymph nodes. Because the methods used to detect these mutations were quantitative,8 the proportion of
tumor cells with mutations could be estimated. As seen in (e) the L858R assay, all the four lesions harbored nearly the same amounts of mutant
and wild-type alleles. In contrast, (f) the T790M mutation was not detected in either sample from the lymph nodes, while two portions of the
regrowing tumor showed modest increases in mutant signals, suggesting that a proportion of the tumor cells had T790M allele.
Figure 4 General schematic of the
molecular classification of lung
cancers. Unsupervised hierarchical
clustering analysis illustrates a molecular classification based on genomewide expression profiles. The upper
panel shows a general schema of the
classification summarizing the results
published to date. Lung cancers are
divided into two large categories with
characteristic features as noted in the
text.
© 2007 The Authors
Journal compilation © 2007 Japanese Society of Pathology
EGFR mutations in lung cancers
Because the secondary refractory mutation is also acquired
in cis, this is suggested to be important to alter the biological significance.47
CLINICOPATHOLOGICAL FEATURES OF EGFR
MUTATIONS
Ethnicity and geographic prevalence
The incidence of EGFR mutations has a distinct ethnic preference. Shigematsu and Gazdar have reviewed this comprehensively.48 They analyzed the incidence of EGFR mutations
in 2347 lung cancer patients according to ethnicity: 33%
of East Asian patients harbored EGFR mutations, whereas
they were seen in only 6% of non-Asian (mostly Caucasian)
patients. When limited to adenocarcinomas, EGFR mutation
were detected in 270/563 (48%) East Asian patients compared with 63/519 (12%) patients of another ethnicity. This
increased prevalence of EGFR mutations is found throughout
East Asian countries, including Korea,20 Taiwan,19 China,24
and Thailand,49 in addition to Japan, but the mutation is less
frequent in African–American21 and Middle East Asian subjects.50 It is open to question whether this skewed distribution
is geographic or ethnic in nature. The high frequency of EGFR
mutations found in second-generation Asian immigrants supports the idea that ethnic rather than geographic differences
are the key. One possible explanation includes polymorphic
variations in EGFR, such as CA dinucleotide repeats in the first
intron and single-nucleotide polymorphisms in the promoter
region. In particular, the numbers of CA dinucleotide repeats
affect EGFR expression levels and the numbers vary according to ethnicity.51–53 The incidence of 20 or more CA repeats is
significantly higher in Asian individuals, whereas 16 or fewer
CA repeats are most common among non-Asian subjects.
This ethnic difference may affect the incidence of interstitial
lung disease related to gefitinib treatment. The incidence is
approximately 10 times higher in Japanese patients (3.5%)
than among non-Japanese (0.3%).54,55
Prevalence of non-smoker and female sex
So far, the majority of the gene alterations found in patients
with lung cancers are reported in association with smoking.
For example, the p53 gene is mutated frequently in smokers
and the smoking-induced G-to-T transversion is common. In
contrast, EGFR mutations are exceptional and it is almost the
sole gene alteration that is inversely related to smoking. Our
analysis on a cohort of 299 patients with lung cancers found
that a negative smoking history is a significant predictive
factor for tumors with EGFR mutations.16,56 One explanation
for this inverse correlation is that because it takes a signifi© 2007 The Authors
Journal compilation © 2007 Japanese Society of Pathology
237
cant time to acquire EGFR mutations, other mutations occur
more quickly in smokers. Indeed, the proportion of nonsmokers among those with EGFR-mutated lung cancers was
not different from that of a sex- and age-matched control
cohort, suggesting that smoking is not a positive risk factor
for EGFR-mutated tumors.57
Similarly, female gender is always listed as a risk factor for
EGFR mutations. Because smoking and sex are highly associated with each other, this suggests that the risk of being
female for acquiring EGFR mutation is simply a matter of this
interaction. However, a case–control study suggested that
sex rather than smoking plays a significant role.57 Because
the estrogen receptor is frequently expressed in NSCLC,
the endocrine environment might be associated with the
mutations.58
Organ specificity
Gene mutations affecting the EGFR kinase domain are
extremely rare in non-pulmonary cancers, whereas alternative splicing and gene amplification without mutations are
common in tumors of the brain, breast, and head and neck
regions. The EGFR mutation was detected in only one case
of colon cancer in an examination of more than 1000 cancers
arising from non-pulmonary organs (Table 1).12,18,59,60
Although several articles noted EGFR mutation in nonpulmonary cancers, most of them were based on paraffinembedded specimens, which can produce PCR artifact.
Indeed, mutations of G-to-A or A-to-G transitions seen in
colon cancers61 was suggested as a consequence of PCR
artifact, such as PCR jumping or post-mortem deamination.62
Associations with other molecules
It has been shown that individual phosphorylated tyrosine
residues in the EGFR can trigger specific downstream signaling pathways through the recruitment of different adaptor
proteins. EGFR involves at least three major signal transduction pathways.18,63,64 Among these, Sordella et al. have
reported constitutive activation of Akt and signal transducer
and activator of transcription (STAT5), but not extracellular
signal-regulated kinase (ERK1/2), in hamster cell lines that
were stably transfected with mutant EGFR.65 Recent analysis
using the cell lines H1650, H3255, and PC-9, shown to harbor
EGFR mutations, suggests a link to activated PI3K/AKT and
STAT3/5 pathways, whereas the RAS/mitogen activated
protein (MAP)/ERK pathway is rarely affected.66–68 These in
vitro results constitute a new puzzle, because they are contradictory to in vivo data showing that the v-Ki-ras2 Kirsten rat
sarcoma viral oncogene homolog (KRAS)/v-raf murine
238
Table 1
Y. Yatabe and T. Mitsudomi
Gene mutation of EGFR kinase domain in non-pulmonary cancers
Tumors examined
Breast
Head and neck
Pancreas
Liver
Stomach
Prostate
Colon
Kidney
Brain
Gall bladder
Bladder
Leukemia
Non-pulmonary, total
Lynch et al.12
Shigematsu et al.18
Lee et al.60
0/141
0/65
0/54
0/31
0/93
0/25
0/20
0/15
0/4
0/54
0/24
0/56
Barber et al.59
Total
1/293
0/265
0/65
0/54
0/73
0/239
0/49
1/467
0/15
0/62
0/50
0/28
0/88
1/1455 (0.0%)
0/73
0/185
0/98
0/58
0/50
0/28
0/324
0/243
0/88
0/537
1/351
EGFR, epidermal growth factor receptor.
sarcoma viral oncogene homolog B1 (BRAF ) pathway plays
an important role in the development of lung cancers. A series
of genes involving the EGFR/RAS/MAP/ERK pathway is
mutated in a mutually exclusive fashion. In the present series
of more than 1000 patients with lung cancers, none of them
simultaneously harbored both EGFR and KRAS gene mutations. Although BRAF and HER2 mutations in lung cancer are
rare,69,70 they are also mutually exclusive.48,71 Similar mutually
exclusive patterns of mutation are seen for RB and p16 in
small cell lung cancers, adenomatosis polyposis coli (APC)
and b-catenin in colorectal cancers, and c-kit and plateletderived factor receptor-a in gastrointestinal stromal tumors,
implying that involvement of this pathway, but not particular
genes, is indispensable for developing these cancers. To
bridge this gap, further examination is clearly warranted.
HISTOLOGICAL FEATURES OF EGFR GENE MUTATED
LUNG ADENOCARCINOMA
Adenocarcinomas with bronchioloalveolar features
Associations between the response to the EGFR-TKI and
histological features were first described by Miller et al.72 In
their multivariate analysis, the histological features of BAC
and smoking status were the only factors that predicted the
response to gefitinib. Prior to that study, they reported the
clinicopathological features of BAC, in which they categorized them into three subtypes: pure BAC, BAC with focal
invasion, and adenocarcinoma with BAC features.73 The
adenocarcinoma with BAC features appearing in the Miller
et al. study72 corresponded to these pure BAC and two variants. After that report there was some confusion about BAC.
Although current World Health Organization (WHO) classification applies very strict criteria of no stromal and vascular
invasion for BAC, many clinicians mistakenly used the term
‘BAC’ to describe an adenocarcinoma mixed subtype with a
predominant BAC pattern. Furthermore, the presence of clinically and biologically different subtypes, mucinous and nonmucinous BAC, in the same category of BAC has made this
confusion profound. The different features of the subtypes
are summarized in Table 2.
Against this background we analyzed the histological features that were characterized by EGFR mutations, using a
cohort of 197 patients with lung cancers.56 Among various
clinicopathological features, only smoking status and cellular
lineage were significant predictive factors. Indeed, EGFR
mutations were specifically involved in a subset of adenocarcinomas that are associated with features of the terminal
respiratory unit. This was overlapped with the gefitinibresponding features of tumors described by Miller et al.,72 but
we had already identified this characteristic subset of lung
adenocarcinomas.74,75
Cancers arising from the terminal respiratory unit
Anatomically and physiologically, the lung is composed of the
bronchial tree and the lung parenchyma, which carry out air
conduction and oxygen exchange, respectively. The epithelium lining the bronchial system includes the bronchial surface
epithelium and bronchial glands, whereas pneumocytes
(types I and II) are lined with parenchymal lung epithelium,
which is uniquely specialized for oxygen exchange. This distinction is also seen in the development of the lung. After the
generation of the two lung buds, branching morphogenesis
generates the bronchial systems, and subsequently the
peripheral parenchyma, namely the terminal sac and then
alveolar space, mature. During the latter phase, development
is regulated by thyroid transcription factor-1 (TTF-1). This
molecule is constantly expressed in the peripheral lung epithelial cells, such as pneumocytes, whereas the epithelium
lining the bronchial system lacks this expression.74–77 Mice
deficient in the gene for TTF-1 die just after birth: although
© 2007 The Authors
Journal compilation © 2007 Japanese Society of Pathology
EGFR mutations in lung cancers
Table 2
239
Characteristics of two biological subtypes in bronchioloalveolar carcinoma
Female
Smoker
Clinical symptom
Radiographic appearance
Phenotype
CK7
CK20
TTF-1
CDX2
Genotype
KRAS
EGFR
Mucinous BAC
Non-mucinous BAC
12/16 (75%)†
5/16 (31%)†
Mucinous sputa
Air-bronchogram, more frequent in
multinodular presentation
44/54 (81%)†
10/54 (19%)†
Mostly no symptom
Ground-glass attenuation
Solid nodular presentation
Positive (>95%)
Mostly positive (70–90%)
Mostly negative
Possible to be positive
Positive (>95%)
Negative
Positive (>90%)
Negative
Frequent (60–70%)
Almost none (<1%)
Occasional (5–10%)
Frequent (>50%)
†Authors’ experience.
BAC, bronchioloalveolar carcinoma; CDX2, caudal type homeobox transcription factor 2; CK, cytokeratin; EGFR, epidermal growth factor receptor ;
KRAS, V-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog; TTF-1, thyroid transcription factor-1.
branching morphogenesis is maintained, maturation of the
peripheral parenchyma is severely impaired, leading to aplasia.78,79 In addition, TTF-1 functions as a transcriptional regulator of many surfactants, which are indispensable to maintain
normal function of the lung.80 Therefore, TTF-1 appear to be a
master regulatory molecule of the peripheral parenchyma,
and hence we refer to the individual unit as the ‘terminal
respiratory unit’, which constitutes the parenchyma.74,75
Among lung cancers, a subset of adenocarcinoma
expresses this master molecule. Examination of the clinicopathological characteristics of TTF-1-expressing cancers
showed that they are specific for adenocarcinomas and are
prevalent among female subjects and non-smokers.74,75 The
morphological features are also affected by the distinction
between bronchial and parenchymal epithelium. TTF-1expressing adenocarcinomas demonstrate high cytological
similarity to pneumocytes and Clara cells, whereas TTF-1negative cancers resemble bronchus-associated epithelium.
It is of note that the molecular pathogenesis may differ
between TTF-1-positive and -negative adenocarcinomas.
TTF-1-positive adenocarcinomas are significantly less frequent in cancer harboring p53 mutations and harboring
altered p27 and prostaglandin-endoperoxide synthase 2
(COX2) expression patterns. In particular, G-to-T transversion of the p53 gene mutation, which is known to be associated with smoking, is rare because smokers are infrequent in
this subset. Taken together, we conclude that there is a
distinct subset of adenocarcinomas characterized by biological resemblance to the epithelium of the terminal respiratory
unit. As mentioned before, all the lung adenocarcinoma harboring EGFR mutations were included in the category of the
terminal respiratory unit-type adenocarcinoma.56
This cellular lineage dependency may be explained by
organ-specific mutation of the EGFR gene. The terminal respiratory unit cells are very unique because this is the sole
© 2007 The Authors
Journal compilation © 2007 Japanese Society of Pathology
epithelium in the human body that functions in gas exchange.
EGFR mutations are acquired only in these cells, as
described previously, and hence they are detected only in the
lung cancers. This uniqueness is also supported by the findings that biological markers of the terminal respiratory unit
serve as distinctive molecules for lung cancers compared
with adenocarcinomas of other organs.81,82
EGFR mutation in the molecular classification
Individual cancers have characteristic expression patterns of
various molecules. Using genome-wide expression profiles,
characteristics of the cancers could be accessed, and their
comparison allows for tumor classification according to biological characteristics.83 Unsupervised hierarchical clustering
in expression profiling is such an example, which illustrates
the molecular classification of tumors, based on the similarity
of genome-wide expression patterns. This new molecularbased classification shares the current pathological classification in part, although it provides additional clues to identify
cancers by their biological groups.
The clustering schema of the lung cancers published so far,
has a shared configuration as shown in Fig. 4, although the
proportion of each cluster varies among the reports.84–87 Lung
cancers can be divided into two distinct branches. One
includes adenocarcinomas alone, and is associated with a
normal expression profile. The other branch consists of all four
other histological subtypes. The former, an adenocarcinoma
subset of the left branch, is characterized by frequent development in female subjects and non-smokers, and expression
of TTF-1 and surfactant proteins. As expected, EGFR mutations are associated with this cluster, and it includes most of
the adenocarcinomas with EGFR mutation.88 These findings
based on genome-wide expression profiles also support the
240
Y. Yatabe and T. Mitsudomi
Table 3 Frequency of EGFR mutation according to histological
subtypes
WHO classification
n
BAC, non-mucinous
Mixed subtype
With BAC pattern
Without BAC pattern
Papillary
Acinar
Others
8
69
29
40
10
4
8
Mutated EGFR
n (%)
5
35
20
15
5
0
2
(63)
(51)
(69)
(38)
(50)
(0)
(25)
Noguchi et al. subtype of small lung adenocarcinomas†
Type A and B
14
9
Type C
31
19
Type D
7
3
Type E
3
0
Type F
2
1
(64)
(61)
(43)
(0)
(50)
†Only adenocarcinomas <2 cm in diameter.93
BAC, bronchioloalveolar carcinoma; EGFR, epidermal growth factor
receptor.
idea of a distinct subset of terminal respiratory unit-type
adenocarcinomas.89 Details of the molecular classification of
lung cancers have been discussed elsewhere.90,91
Correlation with other histological classification
Although nearly half of resected adenocarcinomas harbor
EGFR mutation in Japanese patients, it may be difficult to
recognize the morphology of the adenocarcinoma with EGFR
mutation, namely terminal respiratory unit-type adenocarcinomas. The distinction is best illustrated in Shimosato’s cytological classification of lung adenocarcinomas.92 Among the
six cytological subtypes, Clara cell type, type II alveolar epithelial cell type and their mixed type corresponded to terminal
respiratory unit-type adenocarcinomas, which specifically
involve EGFR mutations. In the WHO classification, because
histological subtypes are defined by various features, such
as being invasive or not (BAC and others), by growth patterns
(papillary and acinar), and by cellular features (fetal), it is
hard to match them with the biological distinction. EGFR
mutations are found among almost all subtypes except for
the acinar subtype (Table 3). Recently, new classifications
have been proposed with the aim of predicting the prognosis
for adenocarcinomas. In one such schema by Noguchi et al.
all of the replacement type (type A–C), type F (papillary type),
and a part of type D (poorly differentiated type) correspond to
terminal respiratory unit-type adenocarcinomas.93 Indeed,
EGFR mutations are detected in these subtypes in our analysis. A similar incidence was reported by a group from National
Cancer Institute in Tokyo.94
Efforts to isolate this characteristic subset of lung adenocarcinomas have been conducted by many pathologists.
Edwards has reported two distinctions of lung adenocarcino-
mas: parenchymal and bronchial types.95 Herrera et al.96 and
Kimula97 focused on the ultrastructural features of the tumor
cells, emphasizing a subset with differentiation to terminal
respiratory epithelium. Clayton also termed peripheral
adenocarcinomas as BAC regardless of stromal invasion,
because of their ultrastructural features of bronchioloalveolar
cells, contrasting to bronchogenic acinar and solid adenocarcinomas.98 Biological peripheral airway cell markers such as
surfactant proteins and Clara cell antigen were used to clarify
the subset of adenocarcinomas by Linnoila et al.99,100 A
similar approach using peripheral airway markers was
carried out by Singh et al.101,102 Although all the pathologists
were aware of the characteristic subset, EGFR mutations
shed further light on this distinction in lung adenocarcinomas.
FUTURE DIRECTIONS
There is a high diversity among lung adenocarcinomas, but
recent findings on EGFR mutations shed new light on a
subset, namely peripheral adenocarcinomas or adenocarcinomas derived from the terminal respiratory unit. This process
is very similar to that seen in breast cancers (Table 4). Since a
molecular classification based on expression profiling was first
proposed by Perou et al. 83 many findings that support the
biological significance of this classification have accumulated.
These include robustness of the classification among different
cohorts of patients;103–105 specific involvement of BRCA1 gene
mutations104,106 and specific types of epigenetic alteration107 in
a particular subset defined by the molecular signature; illustration of similar classification schemes based on a genomewide pattern of allelic imbalance;108 and different responses to
chemotherapeutic reagents.109,110
In the biological classification schemes, the cellular lineage
of the putative origin appears to be the focus, for example,
terminal respiratory unit in lung adenocarcinomas, and
luminal-like and basal-like cells in breast cancers. Susceptibility to a particular carcinogen is likely to differ among cell
types because of intrinsic cellular features and/or anatomical
features, such as carcinogen accessibility and clearance
rate. Carcinogen sites of deposition according to the size of
inhaled particles and accelerated clearance by the ciliated
epithelium in larger bronchi well exemplify this difference.
Therefore, it is reasonable that the cellular lineage is
reflected in the molecular pathogenesis and hence in tumor
characteristics. Indeed, hematological malignancies have
been classified by putative normal counterparts, which correspond to the cellular lineage. Furthermore, a ‘lineageaddiction’ model has been proposed based on the
observation of microphthalmia transcription factor gene
amplification in melanomas.112,113 The survival of cancer cells,
similar to their putative original normal counterparts, is regulated crucially by master molecules of the lineage. Therefore,
© 2007 The Authors
Journal compilation © 2007 Japanese Society of Pathology
EGFR mutations in lung cancers
Table 4
241
Biological classification of breast and lung cancers
Breast cancer
Histological classification
Molecular classification
Robustness of the
classification
Specific involvement of
the subset
Clinical response
Lung cancer
Ductal, lobular and special type
ER-positive and negative
HER2 gene amplified type
Luminal, basal, HER2, normal-like83
SCLC and NSCLC
Ad, Sq, La, AS, and others
Similar classification schema in different cohort103–105
Genome-wide LOH pattern108
HER2 in HER2 subtypes83
BRCA1 in basal subtype104,106
X-chromosomal inactivation in basal subtype107
Trastszumab and HER2 gene amplified cancers
Frequent CR in basal and HER2 subtypes109,110
TRU and non-TRU type88,90
Bronchioid, squamoid, and magnoid91
Similar classification schema in different cohort91
Genome-wide CGH pattern89
EGFR gene in TRU type adenocarcinoma88,91
BRAF gene111
EGFR gene mutation and its TKI
?
Ad, adenocarcinoma; AS, adenosquamous carcinoma; BRAF, V-raf murine sarcoma viral oncogene homolog B1; BRCA1, breast cancer 1, early onset;
CGH, comparative genomic hybridization; CR, complete response; EGFR, epidermal growth factor receptor ; ER, estrogen receptor; La, large cell
carcinoma; LOH, loss of heterozygosity; NSCLC, non-small cell lung cancer; SCLC, small cell lung cancer; Sq, squamous cell carcinoma; TKI, tyrosine
kinase inhibitor; TRU, terminal respiratory unit.
the mechanisms may be involved in a lineage-specific
manner. EGFR as well as TTF-1, which are specifically associated with the subset of lung adenocarcinomas, may follow
a similar scenario. This hypothesis needs to be tested by a
combination of benchtop and clinical research.
ACKNOWLEDGMENTS
The authors wish to thank Takashi Takahashi for invaluable
support and encouragement, Noriko Shibata and Hiroji Ishida
for excellent technical assistance, and to all the members of
the Department of Pathology, Aichi Cancer Center. This work
was supported in part by Grant-in-Aid (C-17590328) from the
Ministry of Education, Culture, Sports, Science and Technology of Japan.
REFERENCES
1 Jemal A, Murray T, Ward E et al. Cancer statistics, 2005. CA
Cancer J Clin 2005; 55: 10–30.
2 D’Addario G, Pintilie M, Leighl NB, Feld R, Cerny T, Shepherd
FA. Platinum-based versus non-platinum-based chemotherapy in advanced non-small-cell lung cancer: A metaanalysis of the published literature. J Clin Oncol 2005; 23:
2926–36.
3 Pfister DG, Johnson DH, Azzoli CG et al. American Society of
Clinical Oncology treatment of unresectable non-small-cell
lung cancer guideline: Update 2003. J Clin Oncol 2004; 22:
330–53.
4 Giaccone G, Smit E. Lung cancer. Cancer Chemother Biol
Response Modif 2003; 21: 445–83.
5 Marshall J. Clinical implications of the mechanism of epidermal
growth factor receptor inhibitors. Cancer 2006; 107: 1207–18.
6 Giaccone G. Epidermal growth factor receptor inhibitors in the
treatment of non-small-cell lung cancer. J Clin Oncol 2005; 23:
3235–42.
© 2007 The Authors
Journal compilation © 2007 Japanese Society of Pathology
7 Janne PA, Engelman JA, Johnson BE. Epidermal growth factor
receptor mutations in non-small-cell lung cancer: Implications
for treatment and tumor biology. J Clin Oncol 2005; 23: 3227–
34.
8 Yatabe Y, Hida T, Horio Y, Kosaka T, Takahashi T, Mitsudomi
T. A rapid, sensitive assay to detect EGFR mutation in small
biopsy specimens from lung cancer. J Mol Diagn 2006; 8:
335–41.
9 Fukuoka M, Yano S, Giaccone G et al. Multi-institutional randomized phase II trial of gefitinib for previously treated patients
with advanced non-small-cell lung cancer. J Clin Oncol 2003;
21: 2237–46.
10 Kris MG, Natale RB, Herbst RS et al. Efficacy of gefitinib, an
inhibitor of the epidermal growth factor receptor tyrosine kinase,
in symptomatic patients with non-small cell lung cancer: A
randomized trial. JAMA 2003; 290: 2149–58.
11 Hirsch FR, Scagliotti GV, Langer CJ, Varella-Garcia M, Franklin WA. Epidermal growth factor family of receptors in preneoplasia and lung cancer: Perspectives for targeted therapies.
Lung Cancer 2003; 41 (Suppl 1): S29–42.
12 Lynch TJ, Bell DW, Sordella R et al. Activating mutations in the
epidermal growth factor receptor underlying responsiveness of
non-small-cell lung cancer to gefitinib. N Engl J Med 2004;
350: 2129–39.
13 Paez JG, Janne PA, Lee JC et al. EGFR mutations in lung
cancer: Correlation with clinical response to gefitinib therapy.
Science 2004; 304: 1497–500.
14 Pao W, Miller V, Zakowski M et al. EGF receptor gene
mutations are common in lung cancers from ‘never smokers’
and are associated with sensitivity of tumors to gefitinib
and erlotinib. Proc Natl Acad Sci USA 2004; 101: 13 306–
11.
15 Weinstein IB. Cancer. Addiction to oncogenes: The Achilles
heal of cancer. Science 2002; 297: 63–4.
16 Kosaka T, Yatabe Y, Endoh H, Kuwano H, Takahashi T, Mitsudomi T. Mutations of the epidermal growth factor receptor
gene in lung cancer: Biological and clinical implications.
Cancer Res 2004; 64: 8919–23.
17 Marchetti A, Martella C, Felicioni L et al. EGFR mutations in
non-small-cell lung cancer: Analysis of a large series of cases
and development of a rapid and sensitive method for diagnostic screening with potential implications on pharmacologic
treatment. J Clin Oncol 2005; 23: 857–65.
18 Shigematsu H, Lin L, Takahashi T et al. Clinical and biological
features associated with epidermal growth factor receptor
242
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
Y. Yatabe and T. Mitsudomi
gene mutations in lung cancers. J Natl Cancer Inst 2005; 97:
339–46.
Huang SF, Liu HP, Li LH et al. High frequency of epidermal
growth factor receptor mutations with complex patterns in nonsmall cell lung cancers related to gefitinib responsiveness in
Taiwan. Clin Cancer Res 2004; 10: 8195–203.
Han SW, Kim TY, Hwang PG et al. Predictive and prognostic
impact of epidermal growth factor receptor mutation in nonsmall-cell lung cancer patients treated with gefitinib. J Clin
Oncol 2005; 23: 2493–501.
Yang SH, Mechanic LE, Yang P et al. Mutations in the tyrosine
kinase domain of the epidermal growth factor receptor in nonsmall cell lung cancer. Clin Cancer Res 2005; 11: 2106–10.
Cappuzzo F, Hirsch FR, Rossi E et al. Epidermal growth factor
receptor gene and protein and gefitinib sensitivity in non-smallcell lung cancer. J Natl Cancer Inst 2005; 97: 643–55.
Bell DW, Lynch TJ, Haserlat SM et al. Epidermal growth factor
receptor mutations and gene amplification in non-small-cell
lung cancer: Molecular analysis of the IDEAL/INTACT gefitinib
trials. J Clin Oncol 2005; 23: 8081–92.
Mu XL, Li LY, Zhang XT et al. Gefitinib-sensitive mutations of
the epidermal growth factor receptor tyrosine kinase domain in
chinese patients with non-small cell lung cancer. Clin Cancer
Res 2005; 11: 4289–94.
Takano T, Ohe Y, Sakamoto H et al. Epidermal growth factor
receptor gene mutations and increased copy numbers predict
gefitinib sensitivity in patients with recurrent non-small-cell
lung cancer. J Clin Oncol 2005; 23: 6829–37.
Greulich H, Chen TH, Feng W et al. Oncogenic transformation
by inhibitor-sensitive and -resistant EGFR mutants. PLoS Med
2005; 2: e313.
Riely GJ, Pao W, Pham D et al. Clinical course of patients with
non-small cell lung cancer and epidermal growth factor receptor exon 19 and exon 21 mutations treated with gefitinib or
erlotinib. Clin Cancer Res 2006; 12: 839–44.
Mitsudomi T, Kosaka T, Endoh H et al. Mutations of the epidermal growth factor receptor gene predict prolonged survival
after gefitinib treatment in patients with non-small-cell lung
cancer with postoperative recurrence. J Clin Oncol 2005; 23:
2513–20.
Ji H, Li D, Chen L et al. The impact of human EGFR kinase
domain mutations on lung tumorigenesis and in vivo sensitivity
to EGFR-targeted therapies. Cancer Cell 2006; 9: 485–95.
Politi K, Zakowski MF, Fan PD, Schonfeld EA, Pao W, Varmus
HE. Lung adenocarcinomas induced in mice by mutant EGF
receptors found in human lung cancers respond to a tyrosine
kinase inhibitor or to down-regulation of the receptors. Genes
Dev 2006; 20: 1496–510.
Arteaga CL. EGF receptor mutations in lung cancer: From
humans to mice and maybe back to humans. Cancer Cell
2006; 9: 421–3.
Rajkumar T, Gullick WJ. The type I growth factor receptors in
human breast cancer. Breast Cancer Res Treat 1994; 29: 3–9.
Chung CH, Ely K, McGavran L et al. Increased epidermal
growth factor receptor gene copy number is associated with
poor prognosis in head and neck squamous cell carcinomas.
J Clin Oncol 2006; 24: 4170–76.
Ekstrand AJ, James CD, Cavenee WK, Seliger B, Pettersson
RF, Collins VP. Genes for epidermal growth factor receptor,
transforming growth factor alpha, and epidermal growth factor
and their expression in human gliomas in vivo. Cancer Res
1991; 51: 2164–72.
Diedrich U, Lucius J, Baron E, Behnke J, Pabst B, Zoll B.
Distribution of epidermal growth factor receptor gene amplification in brain tumours and correlation to prognosis. J Neurol
1995; 242: 683–8.
36 Hirsch FR, Varella-Garcia M, McCoy J et al. Increased epidermal growth factor receptor gene copy number detected by
fluorescence in situ hybridization associates with increased
sensitivity to gefitinib in patients with bronchioloalveolar carcinoma subtypes: A Southwest Oncology Group Study. J Clin
Oncol 2005; 23: 6838–45.
37 Hirsch FR, Varella-Garcia M, Bunn PA Jr et al. Molecular predictors of outcome with gefitinib in a phase III placebocontrolled study in advanced non-small-cell lung cancer. J Clin
Oncol 2006; 24: 5034–42.
38 Varella-Garcia M, Mitsudomi T, Yatabe Y et al. EGFR genomic
gain in Japanese non-small cell lung cancer patients treated
with gefitinib. In: 2006 ASCO Annual Meeting Proceedings
Part I. Alexandria, VA: American Society of Clinical Oncology,
2006; 7164.
39 Yokoyama T, Kondo M, Goto Y et al. EGFR point mutation in
non-small cell lung cancer is occasionally accompanied by a
second mutation or amplification. Cancer Sci 2006; 97: 753–9.
40 Roche-Lestienne C, Soenen-Cornu V, Grardel-Duflos N et al.
Several types of mutations of the Abl gene can be found in
chronic myeloid leukemia patients resistant to STI571, and
they can pre-exist to the onset of treatment. Blood 2002; 100:
1014–18.
41 Hochhaus A, Kreil S, Corbin AS et al. Molecular and chromosomal mechanisms of resistance to imatinib (STI571) therapy.
Leukemia 2002; 16: 2190–96.
42 Kobayashi S, Boggon TJ, Dayaram T et al. EGFR mutation
and resistance of non-small-cell lung cancer to gefitinib. N Engl
J Med 2005; 352: 786–92.
43 Pao W, Miller VA, Politi KA et al. Acquired resistance of lung
adenocarcinomas to gefitinib or erlotinib is associated with a
second mutation in the EGFR kinase domain. PLoS Med 2005;
2: e73.
44 Kosaka T, Yatabe Y, Endoh H et al. Analysis of epidermal
growth factor receptor gene mutation in patients with non-small
cell lung cancer and acquired resistance to gefitinib. Clin
Cancer Res 2006; 12: 5764–9.
45 Toyooka S, Kiura K, Mitsudomi T. EGFR mutation and
response of lung cancer to gefitinib. N Engl J Med 2005; 352:
2136.
46 Bell DW, Gore I, Okimoto RA et al. Inherited susceptibility to
lung cancer may be associated with the T790M drug resistance mutation in EGFR. Nat Genet 2005; 37: 1315–16.
47 Engelman JA, Mukohara T, Zejnullahu K et al. Allelic dilution
obscures detection of a biologically significant resistance
mutation in EGFR-amplified lung cancer. J Clin Invest 2006;
116: 2695–706.
48 Shigematsu H, Gazdar AF. Somatic mutations of epidermal
growth factor receptor signaling pathway in lung cancers. Int J
Cancer 2006; 118: 257–62.
49 Sriuranpong V, Chantranuwat C, Huapai N et al. High frequency of mutation of epidermal growth factor receptor in lung
adenocarcinoma in Thailand. Cancer Lett 2006; 239: 292–7.
50 Al-Kuraya K, Siraj AK, Bavi P et al. High epidermal growth
factor receptor amplification rate but low mutation frequency in
Middle East lung cancer population. Hum Pathol 2006; 37:
453–7.
51 Buerger H, Packeisen J, Boecker A et al. Allelic length of a
CA dinucleotide repeat in the egfr gene correlates with the
frequency of amplifications of this sequence: First results of
an inter-ethnic breast cancer study. J Pathol 2004; 203: 545–
50.
52 Liu W, Innocenti F, Chen P, Das S, Cook EH Jr, Ratain MJ.
Interethnic difference in the allelic distribution of human
epidermal growth factor receptor intron 1 polymorphism. Clin
Cancer Res 2003; 9: 1009–12.
© 2007 The Authors
Journal compilation © 2007 Japanese Society of Pathology
EGFR mutations in lung cancers
53 Liu W, Innocenti F, Wu MH et al. A functional common polymorphism in a Sp1 recognition site of the epidermal growth
factor receptor gene promoter. Cancer Res 2005; 65: 46–53.
54 Ando M, Okamoto I, Yamamoto N et al. Predictive factors for
interstitial lung disease, antitumor response, and survival in
non-small-cell lung cancer patients treated with gefitinib. J Clin
Oncol 2006; 24: 2549–56.
55 Ciardiello F, De Vita F, Orditura M, Tortora G. The role of
EGFR inhibitors in nonsmall cell lung cancer. Curr Opin Oncol
2004; 16: 130–35.
56 Yatabe Y, Kosaka T, Takahashi T, Mitsudomi T. EGFR mutation is specific for terminal respiratory unit type adenocarcinoma. Am J Surg Pathol 2005; 29: 633–9.
57 Matsuo K, Ito H, Yatabe Y et al. Risk factors differ for nonsmall-cell lung cancers with and without EGFR mutation:
Assessment of smoking and sex by a case-control study in
Japanese. Cancer Sci 2006; (Epub ahead of print).
58 Stabile LP, Lyker JS, Gubish CT, Zhang W, Grandis JR, Siegfried JM. Combined targeting of the estrogen receptor and the
epidermal growth factor receptor in non-small cell lung cancer
shows enhanced antiproliferative effects. Cancer Res 2005;
65: 1459–70.
59 Barber TD, Vogelstein B, Kinzler KW, Velculescu VE. Somatic
mutations of EGFR in colorectal cancers and glioblastomas.
N Engl J Med 2004; 351: 2883.
60 Lee JW, Soung YH, Kim SY et al. Absence of EGFR mutation
in the kinase domain in common human cancers besides nonsmall cell lung cancer. Int J Cancer 2005; 113: 510–11.
61 Nagahara H, Mimori K, Ohta M et al. Somatic mutations of
epidermal growth factor receptor in colorectal carcinoma. Clin
Cancer Res 2005; 11: 1368–71.
62 Marchetti A, Felicioni L, Buttitta F. Assessing EGFR mutations.
N Engl J Med 2006; 354: 526–8.
63 Jorissen RN, Walker F, Pouliot N, Garrett TP, Ward CW,
Burgess AW. Epidermal growth factor receptor: Mechanisms
of activation and signalling. Exp Cell Res 2003; 284: 31–53.
64 Arteaga CL. Overview of epidermal growth factor receptor
biology and its role as a therapeutic target in human neoplasia.
Semin Oncol 2002; 29: 3–9.
65 Sordella R, Bell DW, Haber DA, Settleman J. Gefitinibsensitizing EGFR mutations in lung cancer activate antiapoptotic pathways. Science 2004; 305: 1163–7.
66 Janmaat ML, Rodriguez JA, Gallegos-Ruiz M, Kruyt FA,
Giaccone G. Enhanced cytotoxicity induced by gefitinib and
specific inhibitors of the Ras or phosphatidyl inositol-3 kinase
pathways in non-small cell lung cancer cells. Int J Cancer
2006; 118: 209–14.
67 Tracy S, Mukohara T, Hansen M, Meyerson M, Johnson BE,
Janne PA. Gefitinib induces apoptosis in the EGFRL858R
non-small-cell lung cancer cell line H3255. Cancer Res 2004;
64: 7241–4.
68 Sakai K, Arao T, Shimoyama T et al. Dimerization and the
signal transduction pathway of a small in-frame deletion in the
epidermal growth factor receptor. FASEB J 2006; 20: 311–13.
69 Davies H, Bignell GR, Cox C et al. Mutations of the BRAF gene
in human cancer. Nature 2002; 417: 949–54.
70 Stephens P, Hunter C, Bignell G et al. Lung cancer: Intragenic
ERBB2 kinase mutations in tumours. Nature 2004; 431:
525–6.
71 Shigematsu H, Takahashi T, Nomura M et al. Somatic mutations of the HER2 kinase domain in lung adenocarcinomas.
Cancer Res 2005; 65: 1642–6.
72 Miller VA, Kris MG, Shah N et al. Bronchioloalveolar pathologic
subtype and smoking history predict sensitivity to gefitinib in
advanced non-small-cell lung cancer. J Clin Oncol 2004; 22:
1103–9.
© 2007 The Authors
Journal compilation © 2007 Japanese Society of Pathology
243
73 Ebright MI, Zakowski MF, Martin J et al. Clinical pattern and
pathologic stage but not histologic features predict outcome for
bronchioloalveolar carcinoma. Ann Thorac Surg 2002; 74:
1640–46;discussion 6–7.
74 Yatabe Y. Role of expression of thyroid transcription factor-1
in pulmonary adenocarcinoma. In: Hayat MA, ed. Immunohistochemistry and in situ Hybridization of Human Carcinomas. New York: Elsevier Science/Academic Press, 2004;
169–79.
75 Yatabe Y, Mitsudomi T, Takahashi T. TTF-1 expression in
pulmonary adenocarcinomas. Am J Surg Pathol 2002; 26:
767–73.
76 Stahlman MT, Gray ME, Whitsett JA. Expression of thyroid
transcription factor-1 (TTF-1) in fetal and neonatal human lung.
J Histochem Cytochem 1996; 44: 673–8.
77 Ordonez NG. Thyroid transcription factor-1 is a marker of lung
and thyroid carcinomas. Adv Anat Pathol 2000; 7: 123–7.
78 Kimura S, Hara Y, Pineau T et al. The T/ebp null mouse:
Thyroid-specific enhancer-binding protein is essential for the
organogenesis of the thyroid, lung, ventral forebrain, and pituitary. Genes Dev 1996; 10: 60–69.
79 Minoo P, Su G, Drum H, Bringas P, Kimura S. Defects in
tracheoesophageal and lung morphogenesis in Nkx2.1(-/-)
mouse embryos. Dev Biol 1999; 209: 60–71.
80 Whitsett JA, Glasser SW. Regulation of surfactant protein
gene transcription. Biochim Biophys Acta 1998; 1408: 303–
11.
81 Giordano TJ, Shedden KA, Schwartz DR et al. Organ-specific
molecular classification of primary lung, colon, and ovarian
adenocarcinomas using gene expression profiles. Am J Pathol
2001; 159: 1231–8.
82 Shedden KA, Taylor JM, Giordano TJ et al. Accurate molecular
classification of human cancers based on gene expression
using a simple classifier with a pathological tree-based framework. Am J Pathol 2003; 163: 1985–95.
83 Perou CM, Sorlie T, Eisen MB et al. Molecular portraits of
human breast tumours. Nature 2000; 406: 747–52.
84 Bhattacharjee A, Richards WG, Staunton J et al. Classification
of human lung carcinomas by mRNA expression profiling
reveals distinct adenocarcinoma subclasses. Proc Natl Acad
Sci USA 2001; 98: 13 790–95.
85 Garber ME, Troyanskaya OG, Schluens K et al. Diversity of
gene expression in adenocarcinoma of the lung. Proc Natl
Acad Sci USA 2001; 98: 13 784–9.
86 Borczuk AC, Gorenstein L, Walter KL, Assaad AA, Wang L,
Powell CA. Non-small-cell lung cancer molecular signatures
recapitulate lung developmental pathways. Am J Pathol 2003;
163: 1949–60.
87 Tomida S, Koshikawa K, Yatabe Y et al. Gene expressionbased, individualized outcome prediction for surgically treated
lung cancer patients. Oncogene 2004; 23: 5360–70.
88 Takeuchi T, Tomida S, Yatabe Y et al. Expression profiledefined classification of lung adenocarcinoma shows close
relationship with underlying major genetic changes and clinicopathologic behaviors. J Clin Oncol 2006; 24: 1679–88.
89 Shibata T, Uryu S, Kokubu A et al. Genetic classification of
lung adenocarcinoma based on array-based comparative
genomic hybridization analysis: Its association with clinicopathologic features. Clin Cancer Res 2005; 11: 6177–85.
90 Yatabe Y. Molecular classification of tumors with special reference to EGFR mutation in lung cancer. Cancer Chemother
Pharmacol 2006; 58 (Suppl 7): 17–23.
91 Hayes DN, Monti S, Parmigiani G et al. Gene expression profiling reveals reproducible human lung adenocarcinoma subtypes in multiple independent patient cohorts. J Clin Oncol
2006; 24: 5079–90.
244
Y. Yatabe and T. Mitsudomi
92 Shimosato Y. Lung tumors. In: Sternberg SS, Antonioli DA,
Carter D, Mills SE, Oberman HA, Sinard JH, eds. Diagnostic
Surgical Pathology, 3rd edn. Philadelphia: Lippincott Williams
& Wilkins, 1999; 1173–1222.
93 Noguchi M, Morikawa A, Kawasaki M et al. Small adenocarcinoma of the lung. Histologic characteristics and prognosis.
Cancer 1995; 75: 2844–52.
94 Matsumoto S, Iwakawa R, Kohno T et al. Frequent EGFR
mutations in noninvasive bronchioloalveolar carcinoma. Int J
Cancer 2006; 118: 2498–504.
95 Edwards CW. Pulmonary adenocarcinoma: Review of 106
cases and proposed new classification. J Clin Pathol 1987; 40:
125–35.
96 Herrera GA, Alexander CB, DeMoraes HP. Ultrastructual subtypes of pulmonary adenocarcinoma. A correlation with patient
survival. Chest 1983; 84: 581–6.
97 Kimula Y. A histological and ultrastructural study of adenocarcinoma of the lung. Am J Surg Pathol 1978; 2: 253–64.
98 Clayton F. The spectrum and significance of bronchioloalveolar carcinomas. Pathol Annu 1988; 23 (Pt 2): 361–94.
99 Linnoila RI, Jensen SM, Steinberg SM, Mulshine JL, Eggleston JC, Gazdar AF. Peripheral airway cell marker expression in non-small cell lung carcinoma. Association with
distinct clinicopathologic features. Am J Clin Pathol 1992; 97:
233–43.
100 Linnoila RI, Mulshine JL, Steinberg SM, Gazdar AF. Expression of surfactant-associated protein in non-small-cell lung
cancer: A discriminant between biologic subsets. J Natl Cancer
Inst Monogr 1992; 13: 61–6.
101 Singh G, Katyal SL, Torikata C. Carcinoma of type II
peumocytes. PAS staining as a screening test for nuclear
inclusions of surfactant specific apoprotein. Cancer 1982; 50:
946–8.
102 Singh G, Scheithauer BW, Katyal SL. The pathobiologic features of carcinomas of type II pneumocytes. An immunocytologic study. Cancer 1986; 57: 994–9.
103 Sorlie T, Perou CM, Tibshirani R et al. Gene expression
patterns of breast carcinomas distinguish tumor subclasses
with clinical implications. Proc Natl Acad Sci USA 2001; 98:
10 869–74.
104 Sorlie T, Tibshirani R, Parker J et al. Repeated observation of
breast tumor subtypes in independent gene expression data
sets. Proc Natl Acad Sci USA 2003; 100: 8418–23.
105 Sotiriou C, Neo SY, McShane LM et al. Breast cancer classification and prognosis based on gene expression profiles from
a population-based study. Proc Natl Acad Sci USA 2003; 100:
10 393–8.
106 Foulkes WD, Stefansson IM, Chappuis PO et al. Germline
BRCA1 mutations and a basal epithelial phenotype in breast
cancer. J Natl Cancer Inst 2003; 95: 1482–5.
107 Richardson AL, Wang ZC, De Nicolo A et al. X chromosomal
abnormalities in basal-like human breast cancer. Cancer Cell
2006; 9: 121–32.
108 Wang ZC, Lin M, Wei LJ et al. Loss of heterozygosity and its
correlation with expression profiles in subclasses of invasive
breast cancers. Cancer Res 2004; 64: 64–71.
109 Troester MA, Hoadley KA, Sorlie T et al. Cell-type-specific
responses to chemotherapeutics in breast cancer. Cancer Res
2004; 64: 4218–26.
110 Rouzier R, Perou CM, Symmans WF et al. Breast cancer
molecular subtypes respond differently to preoperative chemotherapy. Clin Cancer Res 2005; 11: 5678–85.
111 Naoki K, Chen TH, Richards WG, Sugarbaker DJ, Meyerson
M. Missense mutations of the BRAF gene in human lung
adenocarcinoma. Cancer Res 2002; 62: 7001–3.
112 Garraway LA, Widlund HR, Rubin MA et al. Integrative
genomic analyses identify MITF as a lineage survival oncogene amplified in malignant melanoma. Nature 2005; 436:
117–22.
113 Garraway LA, Sellers WR. Lineage dependency and lineagesurvival oncogenes in human cancer. Nat Rev Cancer 2006; 6:
593–602.
© 2007 The Authors
Journal compilation © 2007 Japanese Society of Pathology
本文献由“学霸图书馆-文献云下载”收集自网络，仅供学习交流使用。
学霸图书馆（www.xuebalib.com）是一个“整合众多图书馆数据库资源，
提供一站式文献检索和下载服务”的24 小时在线不限IP 图书馆。
图书馆致力于便利、促进学习与科研，提供最强文献下载服务。
图书馆导航：
图书馆首页
文献云下载
图书馆入口
外文数据库大全
疑难文献辅助工具