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Colon cancer
Epidemiology
3rd most common cancer in males and
females
Accounts for 11% of cancer deaths.
In 2000, 130,200 cases (colon and rectum).
Lifetime risk 6%.
Epidemiology
Rare before the age of 40y, rapid increase
at 50y.
At presentation 37% localized, 37%
regional, 20% metastatic.
1 and 5y survival is 80% and 61% overall.
IBD, FAP, HNPCC, are at inc risk
ascending colon 11%
transverse colon 4%
descending colon 9%
sigmoid colon and rectum
76%
5year survival
World
50-60%
25-30% Poland
Introduction:
Many colorectal cancers are thought to arise from
adenomatous polyps in the colon. These
mushroom-like growths are usually benign, but
some may develop into cancer over time.
Polyps may be small and produce few, if any,
symptoms. Regular screening tests can help
prevent colon cancer by identifying polyps before
they become cancerous.
Your best chance for surviving
colorectal cancer is detecting it
early.
When found early, there is nearly a
90 percent chance for cure.
Symptoms:
There often are no symptoms of colorectal
cancer in its early stages. Most colorectal
cancers begin as a polyp.
As polyps grow, they can bleed or obstruct
the intestine.
When the disease spreads, it is still called
colorectal cancer
Symptoms:
 rectal bleeding
 blood in the stool or toilet after a bowel movement
 prolonged diarrhea or constipation
 a change in the size or shape of the stool
 A change in bowel movement pattern that continues over
time
 General discomfort in the abdomen (frequent gas pains,
cramping pain, feeling of bloating or fullness)
 Vomiting
 Constant fatigue
 Chronic constipation
Risk Factors:
•
Age: Colorectal cancer is most common in people over
50.
• Family history: Your risk is higher with a family history
(especially parent, sibling) of colorectal cancer, or
adenomatous polyps.
• Personal history: Your risk is higher with a personal
history of inflammatory bowel disease (Crohn’s disease
or colitis), colon cancer, or adenomatous polyps.
•
Weight: Lack of physical activity and obesity are risk
factors.
• Diet: A high-fat diet, particularly animal fats, may
Increase your risk. Diets high in fruits and Vegetables are
thought to decrease your risk. diets high in red and
processed meat, as well as those low in fiber, are
associated with an increased risk of colorectal cancer.
Individuals who frequently eat fish showed a decreased
risk
•
Cigarette smoking and alcohol: Your risk may be
higher if you smoke or drink
• Physical inactivity: People who are physically active
are at lower risk of developing colorectal cancer.
Risk Factors
Polyps-Most cancers arise from them.
Classified as neoplastic (adenomatous)which are
benign or malignant, and nonneoplastic (hyperplastic,
mucosal, inflammatory, hamartomaous).
Adenomatous polyps found in 33% of people by age
50, 50% by age 70.
Most lesions <1cm, 60% single, 40% multiple.
Invasive cancer will develop in 24% when untreated.
Polyps
Three variants: Tubular(75-87%),
tubulovillous (8-15%), Villous(5-10%).
Tubulovillous, villous(most in rectum) have
most increased risk of cancer 20% and
40% respectively.
Size, degree of dysplasia (46% cancer
>2cm, 34% in severe dysplasia).
Treatment
Endoscopic removal, surveillance every
three years.
Biopsy if it can’t be removed.
Surgery for those not amenable to safe
polypectomy (large sessile villous lesions).
Treatment
Fungation, ulceration, distortion are contraindications
for polypectomy.
Colectomy indicated for residual carcinoma, those at
high risk for +LN despite complete polypectomy.
+margin, poor diff, level 4, vascular, lymphatic
invasion.
Sessile polyp with invasive cancer should be
considered for resection even if no high risk pathologic
features.
Weigh all against pts medical condition of course.
Hereditary Polyposis Syndromes
All have this in common: Multiple intestinal
polyps, extraintestinal manifestations.
FAP: 1-2% of colon cancer patients. A point
mutation of APC gene on chromosome 5,
band q21.
Polyps found throughout the GI tract but
most in colon. Symptoms manifest by ages
16-50.
Cancer will develop in all by age 50.
Familial Adenomatous
Polyposis (FAP)
Familial adenomatous polyposis (FAP) is a
genetic condition where affected individuals will
develop hundreds to thousands of polyps
If a parent has FAP, each child has a 50% (or, 1
in 2) chance of inheriting FAP. Each child also
has a 50% chance of not inheriting FAP. FAP
does not skip generations. Both males and
females are equally likely to be affected.
Therefore, if you have FAP, your children each
have a 1 in 2 chance of having FAP.
Hereditary Polyposis Syndromes
Gardner’s Syndrome: Variant of FAP.
Colonic and extracolonic manifestations.
Periampulary lesions, duodenal lesions,
gastric polyps.
Ocular, cutaneous, skeletal (retinal,
mandible, jaw, teeth, sebaceous cysts).
Desmoids, hepatoblastoma, thyroid cancer,
Turcot’s syndrome (brain).
Hereditary Nonpolyposis
Syndromes
Lynch I and II. Occurs five times more
frequently than familial polyposis. 1-5 % of
colon cancers. Lynch I just colon, Lynch II
also involves endometrium, ovary, stomach,
small bowel, biliary, pancreas, ureter, renal
pelvis.
85% lifetime risk of colon cancer, more right
sided cancers (60-70%), earlier (45y), lower
stage, better survival, but 20% risk of
metachronous, synchronous lesions.
Inflammatory Bowel Disease
Ulcerative colitis carries a risk of colorectal
carcinoma 30 times greater than general
population.
Risk increases with duration of disease.
After 30 years, risk increases to 35%
Crohn’s disease associated with 10-20 fold
increased risk of cancer.
Need to do surveillance in these population.
Previous Colon Cancer
A second primary colon cancer is three
times more likely to develop in patients with
a history of colon cancer.
Metachronous lesions develop in 5-8% of
patients.
History of First-Degree Relatives
People with first-degree relatives with
colorectal cancer have a 1.8-8 fold increase
risk of colorectal cancer.
Risk is higher if more than one relative
affected.
Risk is higher if developed in the relative at
a young age.
Pathology
>90% adenocarcinomas. Four morphologic
variants.
Ulcerative (most common), exophytic
(polypoid, fungating), annular (classic
applecore), submucosal infiltrative(linnitus
type).
Grading system 1-3. Most developed to
least differentiated glandular structures.
The Layers of the Wall
Colon Wall
Staging
A- to submucosa only
B1- to muscularis only
B2- thru wall, not adjacent.
B3- Adjacent organs involved.
C1- B1 plus LN
C2- B2 plus LN
C3- B3 plus LN
D- Distant mets
A
-- 95 - 100 %
B -- 72 - 80%
C -- 26 - 34
%
D -0- 2 %
Staging-TNM
T1 invades submucosa
T2 invades muscularis
T3 invades subserosa
T4 invades organs outside
N1- 1-3 nodes
N2- 4 or more nodes
N3- central nodes
M0- no mets
M1- distant mets
Clinical Presentation
Bleeding, pain, bowel habit changes, weight loss,
anorexia, nausea, vomiting, fatigue, anemia.
Right upper quadrant pain, fevers sweats,
hepatomegaly, ascites, effusions, adenopathy(METS).
Obstruction(5-15%) increases risk of death 1.4 fold.
Perforation (6-8%) increases it 3.4 fold.
Stage I 15%, Stage II 30%, Stage III 20%, Stage IV
25%.
Obstruction less common on right side.
Liver Mets
Colon Cancer
DIAGNOSIS:
Colorectal cancer screening rates remain
low. Therefore, screening for the disease is
recommended in individuals who are at
increased risk. There are several different
tests available for this purpose.
Continue
• Digital rectal exam (DRE): The doctor inserts a
lubricated, gloved finger into the rectum to feel
for abnormal areas. It only detects tumors large
enough to be felt in the distal part of the rectum
but is useful as an initial screening test.
• Fecal occult blood test (FOBT): a test for blood
in the stool. Two types of tests can be used for
detecting occult blood in stools i.e. guaiac based
(chemical test) and immunochemical. The
sensitivity of immunochemical testing is superior
to that of chemical testing without an
unacceptable reduction in specifity.
• Endoscope:
– Sigmoidoscopy: A lighted probe (sigmoidoscope) is
inserted into the rectum and lower colon to check for
polyps and other abnormalities.
– Colonoscopy: A lighted probe called a colonoscope is
inserted into the rectum and the entire colon to look
for polyps and other abnormalities that may be
caused by cancer. A colonoscopy has the advantage
that if polyps are found during the procedure they can
be immediately removed. Tissue can also be taken for
biopsy.
Diagnosis
Scope, Chest X-ray, Complete blood count,
CEA, Localized Fibrous Tumors
Preop CT scan? Some get it for abnormal
LFTs only (but only 15% of liver mets have
abnormal LFTs). Others will get it if large
bulky tumors to see about adjacent organs,
LN.
10% of mets are missed with preoperative
and operative evaluations, IOUS best for
this.
Diagnosis
15-20% liver mets not palpable.
Preop CEA reflects prognosis, disease
extent (over 10-20 poor)
CEA may not be elevated in poorly
differentiated or rectal cancers.
CEA really only good for follow up.
Rectal Cancer
In addition to History&Physical, CXR, CBC,
LFTs, EUS, Proctoscopic exam, full
colonoscopy, CT scan should be done for
rectal cancer.
Accurate preoperative staging critical
because stage may influence treatment
decisions such as trans anal excision,
preop chemoradiation.
Rectal Cancer
EUS is most accurate tool in determining tumor stage
with all layers identified with 67-93% accuracy.
Differentiating T1 from T3 easy but T2 from T3 harder.
Limitations of EUS: operator experience, differentiating
LN vs.blood vessels, post radiation changes, stenotic
lesions, overstaging (10-15%), understaging (1-2%).
Superior to CT or MRI for depth of tumor.
Rectal Cancer

Lymph node staging more difficult. EUS 62-83%
accurate, CT scan 35-73% accurate.
All these tests pick up size of LN only.
50-75% of involved LN are normal in size, so may not
be picked up. Similarly, enlarged LN may be
inflammatory, so false negative.
LN> 3mm and hypoechoic are likely to have
malignancy, also FNA might help under EUS
guidance.
Rectal Cancer
CT scanning of abdomen and pelvis is
important for other organ involvement, and
distant spread.
CT is better than EUS for contiguous organ
involvement.
Pathology:
The pathology of the tumor is usually
reported from the analysis of tissue taken
from a biopsy or surgery. A pathology report
will usually contain a description of cell type
and grade. The most common colon cancer
cell type is adenocarcinoma which accounts
for 95% of cases. Other, rarer types include
lymphoma and squamous cell carcinoma.
Cancers on the right side (ascending colon
and cecum) tend to be exophytic, that is, the
tumour grows outwards from one location in
the bowel wall. This very rarely causes
obstruction of feces, and presents with
symptoms such as anemia. Left-sided
tumours tend to be circumferential, and can
obstruct the bowel much like a napkin ring.
1-Surgery and treatment:
Colectomy with Ileorectostomy
(Ileorectal Anastomasis)
In this procedure, the colon is
removed, but all or most of the
rectum is left in place. The small
intestine is attached to the upper
portion of the rectum.
Most patients maintain very good
bowel function, though antidiarrhea medications are
sometimes needed. This
procedure is typically
recommended when there are
very few polyps in the rectum.
.
.
Restorative
Proctocolectomy (Ileal
Pouch Anal Anastomosis)
• This operation involves removing the entire
colon and most of the rectum. A new rectum,
or reservoir for stool, called a pouch, is made
out of the lower end of the small intestine
(ileum).
The pouch is joined to the anus so bowel
movements can flow in the normal way. A
temporary ileostomy, or a stoma where the
waste empties into a bag through the abdominal
wall, is usually needed to help heal this delicate
connection.
Restorative Proctocolectomy
(Ileal Pouch Anal Anastomosis)
Chemotherapy
Chemotherapy is used to reduce the likelihood of
metastasis developing, shrink tumor size, or slow
tumor growth. Chemotherapy is often applied after
surgery (adjuvant), before surgery (neo-adjuvant),
or as the primary therapy (palliative). The
treatments is to improve survival and/or reduce
mortality rate, In colon cancer, chemotherapy after
surgery is usually only given if the cancer has
spread to the lymph nodes (Stage III)
Life Style and Nutrition
• The comparison of colorectal cancer incidence
in various countries strongly suggests that
sedentarily, overeating (i.e., high caloric intake),
and perhaps a diet high in meat (red or
processed) could increase the risk of colorectal
cancer
• In contrast, a healthy body weight, physical
fitness, and good nutrition decreases cancer risk
in general.
• Accordingly, lifestyle changes could decrease the risk of
colorectal cancer as much as 60-80%.
• A high intake of dietary fiber (from eating fruits,
vegetables, cereals, and other high fiber food products)
has, until recently, been thought to reduce the risk of
colorectal cancer
• Calcium or folic acid (a B vitamin), aspirin are able to
decrease carcinogenesis in pre-clinical development
models: Some studies show full inhibition of carcinogeninduced tumors in the colon of rats.
Screening
FOBT, DCBE, endoscopy most useful screening
methods.
FOBT detects cancer at an earlier stage, with
reduction in cancer deaths.
Flexible sigmoidoscopy and polyp clearance has
resulted in decreased colon cancer.
Value of full colonoscopy is noted since 40% of colon
cancers occur proximal to splenic flexure.
DCBE used if pt refuses scope, or poor scope, etc.
Barium Enema Sigmoid Cancer
Screening
CEA has no role in in screening for primary
lesions. False positives occur in benign
disease(lung, liver, bowel) as well as
malignancies of pancreas, breast ovaries,
prostate, head and neck, bladder, kidney.
CEA increased in smokers.
60% of tumors will be missed by CEA
alone.
Recommendations
Age>50 asymptomatic, average risk.
FOBT yearly, scope if positive
Flex sigmoidoscopy every 5y (full colon if +)
Increased risk: Same but start age 40.
Recommendations
Hx of HNPCC: Full colon every 1-2y (2030y) then full colon yearly after 40y.
Hx Aden Polyps: repeat in 3y, second exam
normal repeat 5y.
Hx Colon cancer: Full colon within 1y, if
second normal repeat 3y, if next normal
every 5y.
FAP: Counseling, Flex Sigmoid every 12
months.
Benefits of Screening
 Cancer Prevention
Removal of pre-cancerous polyps prevent cancer
(unique aspect of colon cancer screening)
Improved Survival 
Early detection markedly improves chances of long
term survival
Colorectal Screening Rates
 Just 40% of colorectal cancers are detected at
the earliest stage
 A little more than half of Americans over age 50
report having had a recent colorectal cancer
screening test
 Slow but steady improvement in these numbers
over the past decade (but all are not benefiting
to the same degree)