Download Mirmiran-SBRT for Early Stage Lung Cancer

SBRT for Early
Stage Lung Cancer
Ali Mirmiran, MD
Nebraska Methodist Hospital
March 4, 2014
Objective
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To discuss the role of stereotactic body
radiotherapy (SBRT) in early stage lung
cancer
Epidemiology
Lung cancer is the most frequent cause of
cancer death in men & women (28% of all
cancer deaths)
 There are more deaths from lung cancer in
the United States than from cancers of the
breast & prostate combined
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85% of lung cancer is NSCLC
25% have stage 1 or stage 2 disease at
diagnosis
Optimal mgmt for these stages is surgery 
60-80% 5 yr survival for stage I, as compared
to 15-30% for conventional RT
In the treatment of early-stage NSCLC,
radiotherapy has played only a minor role,
because surgery delivers superior results, as
compared with conventional RT
In patients with comorbidities, especially of
cardiovascular origin, radiotherapy is often the
only therapeutic alternative
Conventional RT
5 year survival rate ranges from 10-30%
 5 yr LC about 50%
 Avg dose 60-70 Gy in 1.8-2.0 Gy fractions
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What is SBRT?
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An ablative therapy where potent doses of
radiation are directed at tumors with known
boundaries
Prescriptions of few fractions & large doses are
used
Initially, applied to intracranial tumors
Lax & Blomgren (Sweden) were the first to apply
it to extracranial tumors
Requirements for SBRT
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Medically inoperable?
 Baseline
FEV1 < 40% predicted
post-op FEV1 <30% predicted
 DLCO < 40% predicted
 PO2 < 70 mm Hg
 PCO2 > 50 mm Hg
 Other conditions
 Likely
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Continued stability in body frame for
longer than 30 minutes
SBRT Set-up & Planning
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Standard immobilization device is a firm frame
(e.g. Elekta Body Frame) & vacuum pillow
system
Restricting respiratory movement throughout
treatment is helpful for accuracy
Three different techniques which may be used to
restrict respiratory movements include
dampening/inhibition, gating, & tracking
Dampening/inhibitory technique is the most
common method which uses an abdominal
compression device
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Tumor Tracking
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Respiratory Gating
Playback
Indicator
Breathing Signal
Upper Threshold
Lower Threshold
Beam On / Off
Indicator
Treatment and Dosing
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SBRT mimics the radiosurgery concept of using many
beams which converge on the target
The beams can be non-coplanar
Imaging can be done with 4D CT
Treatment doses are in the range of 50-60 Gy in three to
five fractions, however no uniform standard yet
Normal tissue- must limit dose
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Spinal cord, esophagus, brachial plexus, heart, trachea,
bronchus, etc … limit to about 6-10 Gy / fx
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Overall survival rate according to the
biologic effective dose in medically
operable patients
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Onishi et al 2004: Results
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Local recurrence: 33 patients (15%)
 26.4%
for BED < 100 Gy, 8.1% for BED ≥ 100 Gy
(p < 0.05)
No difference in local recurrence between
stage IA & Stage IB when treated with BED ≥
100 Gy
 BED ≥ 100 Gy necessary for optimal control
 BED = nd [(1+d)/ α/β]
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 (α/β)
= 10 Gy
Onishi et al, 2004
Onishi et al, 2004
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Take home point: Survival rates in
selected patients (medically operable,
BED >100 Gy) were excellent, &
potentially comparable to those of surgery
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Evaluating SBRT: Challenges
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Problems with interpreting local control
 Local normal tissue effects
 Pt death before follow-up
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cloud interpretation
Differences in definition of local control
Differences in dosing & fractionation
schedule
Confounding factors: prior XRT treatment,
chemo
Separating out medically inoperable grp from
refused surgery grp
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Kimura et al, 2006: CT Appearance of Radiation Injury of
the Lung and Clinical Symptoms After SBRT for Lung
Cancers; are Patients with Pulmonary Emphysema also
Candidates for SBRT for Lung Cancers?
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Purpose: analyze CT appearance of radiation injury to the
lung & evaluate appearance in patients with emphysema
45 patients with 52 primary or metastatic lesions
Median age 75
Dose 54-60 Gy total, 8-14 fx
Follow-up CTs done at 1,3,6, then every 6 months
Kimura et al, 2006: Results
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Acute radiation pneumonitis (< 6 months after SBRT)
had 5 patterns:
 Diffuse consolidation: 38.5%
 Patchy consolidation & ground glass opacities (GGO):
15.4%
 Diffuse GGO: 11.5%
 Patchy GGO: 2.0%
 No evidence of increasing density:32.6%
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Classification of Radiation Fibrosis (> 6 months after
SBRT)
 Modified Conventional Pattern: 61.5%
 Mass-like Pattern: 17.3%
 Scar-like Pattern: 21.2%
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Kimura et al, 2006
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Most patients with no evidence of
increased density pattern & the scar like
pattern also had emphysema (p <.00038,
0.00044, respectively)
Diffuse consolidation pattern; a 78-year-old woman
with Stage IB lung cancer (adenocarcinoma), 60 Gy/8
fractions (a) before SBRT, (b) 2 months after SBRT
A 74-year-old man with metastatic lung cancer from lung cancer
(squamous cell carcinoma), 56 Gy/14 fractions. This case was
diagnosed as pulmonary emphysema Grade 2, no evidence of
increasing density pattern as acute radiation pneumonitis, &
scar-like pattern as radiation fibrosis. (a) Before SBRT, (b) 3
months after SBRT, (c) 20 months after SBRT
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Typical Appearance of Radiation
Injury After SBRT
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~ 1 month after SBRT: no radiologic change
3-6 months: diffuse or patchy consolidation in
the high-dose region & diffuse or patchy GGO in
the low-dose region – radiation pneumonitis
6-9 months: solid or dense consolidation, which
usually move toward the mediastinum or hilum
with shrinkage
1-2 yrs: stable opacities
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Clinical Trials
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Subjects for Further Investigation
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SBRT as a boost after conventional RT
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SBRT vs Surgery in medically operable
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Optimal dosing
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Conclusions
Overall, SBRT studies showed better LC & OS
than conventional RT with minimal toxicity.
SBRT is becoming/has become the standard for
medically inoperable stage I NSCLC
It could potentially become first-line treatment in
operable patients
It is hoped the stereotactic treatments not only will give
medically frail patients with early stage lung cancer a
choice but perhaps someday be another option for a
larger spectrum of lung cancer patients. -Robert
Timmerman, MD
Special thanks to Dr. Hauke
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