2. Outline
•
•
•
•
•
Where is the colon and what does it do?
Why is colon cancer important?
• How many cases/year?
• Who gets it?
• Who dies from it?
How does colon cancer develop?
How is colon cancer treated?
Is colon cancer preventable?
3.
4. What is the Function of the Colon
and Rectum?
•
The colon and rectum
comprise the large
intestine (large bowel)
•
The primary function
of the large bowel is to
turn liquid stool into
formed fecal matter
5.
6. What is Colorectal Cancer?
•
Third most common type of cancer and
second most frequent cause of cancerrelated death
•
A disease in which normal cells in the lining
of the colon or rectum begin to change, grow
without control, and no longer die
•
Usually begins as a noncancerous polyp that
can, over time, become a cancerous tumor
7. Colon; The Cancer Its Self
•
•
•
It starts with a simple
cell the mutates and
grows into a polyps
If a polyp is allowed to
remain in the colon it
can grow into a
cancerous tumor that
can invade other
organs.
Colon cancer is the
second leading cause
of cancer deaths
11. What Are the Risk Factors
for Colorectal Cancer?
•
•
•
•
•
•
•
•
Polyps (a noncancerous or precancerous
growth associated with aging)
Age
Inflammatory bowel disease (IBD)
Diet high in saturated fats, such as red meat
Personal or family history of cancer
Obesity
Smoking
Other
12. What Are the Symptoms of
Colorectal Cancer?
•
A change in bowel habits: diarrhea, constipation, or
a feeling that the bowel does not empty completely
•
Bright red or dark blood in the stool
•
Stools that appear narrower or thinner than usual
•
Discomfort in the abdomen, including frequent gas
pains, bloating, fullness, and cramps
•
Unexplained weight loss, constant tiredness, or
unexplained anemia (iron deficiency)
13. Symptoms of Colon Cancer
•
•
•
•
•
Persistent
Constipation
Diarrhea
Blood in the Stool
Unexplained Fatigue
14. Colorectal Cancer and Early Detection
•
Colorectal cancer can be prevented through
regular screening and the removal of polyps
•
Early diagnosis means a better chance of
successful treatment
•
Screening should begin at age 50 for all
“average risk” individuals or sooner if you
have a family history of colorectal cancer,
symptoms, or a personal history of
inflammatory bowel disease
15. How is Colorectal Cancer
Evaluated?
•
Diagnosis is confirmed with a biopsy
•
Stage of disease is confirmed by
pathologists and imaging tests, such as
computerized tomography (CT or CAT)
scans
•
Endoscopic ultrasound and magnetic
resonance imaging (MRI) may also be used
to stage rectal cancer
17. Colon Cancer Preventions
•
Colon cancer can be
prevented and cured
through early detection
•
Changing your eating
habits( more fiber and
less fats)
•
Don’t smoke and drink
less
18. Screening Techniques for
Colorectal Cancer
Fecal occult blood test (FOBT) every year, or
Flexible sigmoidoscopy every 5 years,or
A fecal occult blood test every year plus flexible
sigmoidoscopy every 5 years (recommended by
the American Cancer Society), or
Double-contrast barium enema every 5 to 10
years, or
Colonoscopy every 10 years (recommended by
the American College of Gastroenterology).
19. Screening For Colon Cancer
SAVES LIVES!!!
Test
Mortality
Reduction
Fecal occult blood testing
33%
Flexible sigmoidoscopy
66%
(in portion of colon examined)
FOBT + flexible sigmoidoscopy
43%
(compared to sigmoidoscopy alone)
Colonoscopy
(after initial screening and polypectomy)
~76-90%
20. Colorectal cancer screening
First assess RISK
AVERAGE RISK INDIVIDUAL
• All patients age 50 years and older, the
asymptomatic general population
HIGH RISK
• Personal history – polyp or cancer
• Family history – polyp or cancer in first
degree relatives
21. Fecal Occult Blood Testing
•
•
•
Examination of stool for occult (“hidden”)
blood
Can detect one teaspoon or less of blood
in a bowel movement
Uses chemical reaction between blood
and reagent
23. Double-contrast Barium Enema
•
•
Pros
• Examines entire colon
• Relatively low cost
Cons
• Never studied as a screening test
• Missed 50% of polyps > 1cm in one study
• Detects 50-75% of cancers in those with
positive FOBT
• Interval between exams unknown
Winawer et al. Gastroenterology 1997; 112:599
Rex, Endoscopy 1995; 27:200
Lieberman et al. N Engl J Med 2000; 343:163
26. Flexible sigmoidoscopy
•
•
Pros
• May be done in office
• Inexpensive, cost-effective
• Reduces deaths from rectal cancer
• Easier bowel preparation, usually done without
sedation
Cons
• Detects only half of polyps
• Misses 40-50% of cancers located beyond the
view of the sigmoidoscope
• Often limited by discomfort, poor bowel
preparation
Selby et al N Engl J Med 1992; 336:653
Newcomb et al. JNCI 1992; 84:1572
Rex et al. Gastrointest Endosc 1999; 99:727
Stewart et al Aust NZ J Surg 1999; 69:2
Painter et al Endoscopy 1999; 3:269
27. Colonoscopy
•
•
Pros
• Examines entire colon
• Removal of polyps performed at time of exam
• Well-tolerated with sedation
• Easier bowel preparation, usually done without
sedation
Cons
• Expensive
• Risk of perforation, bleeding low but not negligible
• Requires high level of training to perform
• Miss rate of polyps < 1 cm ~25%, > 1 cm ~5%
Rex et al. Gastroenterology 1997; 112:24-8
Postic et al. Am J Gastroenterol 2002; 97:3182-5
28. Chemopreventive agents
Fiber
Not effective
Aspirin
May be effective
NSAIDs (ibuprofen, etc)
Probably effective
Vitamin E, vitamin C, beta Not effective
carotene
Folate
Effective if obtained in
diet
Calcium
Effective
Estrogen
Effective, but has other
problems
29. Future techniques for colorectal
cancer screening
•
Stool DNA testing
•
Capsule endoscopy (Givens capsule)
•
CT colography (virtual colonoscopy)
34. Cancer Treatment: Surgery
•
Foundation of curative therapy
•
The tumor, along with the adjacent healthy
colon or rectum and lymph nodes, is
typically removed to offer the best chance
for cure
•
May require temporary or (rarely) permanent
colostomy (surgical opening in abdomen that
provides a place for waste to exit the body)
35. Surgery
•
Surgery or "resection" of the colon
involves cutting away the portion of the
colon that is diseased, and reconnecting
the two healthy parts (anastomosis).
36. Surgery
•
In a small percentage of patients with
colon cancer (about 15 percent) the
surgeon will be unable to reconnect the
healthy parts. In such a case, a temporary
or permanent colostomy is used.
•
A colostomy is a surgical opening (stoma)
through the wall of the abdomen into the
colon, which provides a new path for
waste material to leave the body.
37.
38. Cancer Treatment: Chemotherapy
•
Drugs used to kill cancer cells
•
Typical medications include fluorouracil (5FU), oxaliplatin (Eloxatin), irinotecan
(Camptosar), and capecitabine (Xeloda)
•
A combination of medications is often used
39. Types of Chemotherapy
•
Adjuvant chemotherapy is given after surgery
to maximize a patient’s chance for cure
•
Neoadjuvant chemotherapy is given before
surgery
•
Palliative chemotherapy is given to patients
whose cancer cannot be removed to delay or
reverse cancer-related symptoms and
substantially improve quality and length of life
40. Cancer Treatment: Radiation
Therapy
•
The use of high-energy x-rays or other
particles to destroy cancer cell
•
Used to treat rectal cancer, either before
or after surgery
•
Different methods of delivery
•
External-beam: outside the body
•
Intraoperative: one dose during surgery
41. New Therapies: Antiangiogenesis
Therapy
•
“Starves” the tumor by disrupting its
blood supply
•
This therapy is given along with
chemotherapy
•
Bevacizumab (Avastin) was approved by
the U.S. Food and Drug Administration
(FDA) in 2004 for the treatment of stage IV
colorectal cancer
42. Future Research
•
You may have heard
that taking aspirin
prevents colon cancer.
This is an exciting area
of research, and studies
are currently underway
to evaluate whether
aspirin can prevent the
recurrence of
precancerous colon
polyps.
43. Follow-Up Care
•
Doctor’s visits
•
Serial carcinoembryonic antigen (CEA)
measurements are recommended
•
Colonoscopy one year after removal of
colorectal cancer
•
Surveillance colonoscopy every three to
five years to identify new polyps and/or
cancers
Notes de l'éditeur
17. Site Distribution
At one time, conventional wisdom held that half of all colorectal tumors could be reached with the examining finger, or at least the rigid sigmoidoscope. This reflects the distal predominance of colorectal cancer, whose distribution roughly corresponds to that of adenomas. A gradual shift toward a more proximal distribution may be occurring. Whether this is due to improved detection of right-sided tumors, to a change in dietary carcinogen-related exposure of the mucosa, or to other factors, is unknown.
• Vukasin AP, Ballantyne GH, Flannery JT, et al: Increasing incidence of cecal and sigmoid carcinoma. Data from the Connecticut Tumor Registry. Cancer, 66:2442-9, 1990.
• Shinya Y, Wolff WI: Morphhology, anatomic discribution, and cancer potential of colonic polyps. Ann Surg, 190:679-83, 1979.
