Knowing Cancer of Colon

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  • 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.

Transcript

  • 1. ColoreCtal CanCer Dato’ Dr Minder Singh Consultant Surgeon KEDAH MEDICAL CENTRE
  • 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. 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
  • 4. 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
  • 5. 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
  • 6. How Does Colorectal Cancer Develop?
  • 7. Colon Polyp
  • 8. Colon Cancer
  • 9. 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
  • 10. 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)
  • 11. Symptoms of Colon Cancer • • • • • Persistent Constipation Diarrhea Blood in the Stool Unexplained Fatigue
  • 12. 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
  • 13. 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
  • 14. Is Colorectal Cancer Preventable? YES! • Screening • Chemoprevention
  • 15. 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
  • 16. 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).
  • 17. 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%
  • 18. 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
  • 19. 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
  • 20. Double-contrast Barium Enema
  • 21. 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
  • 22. Sigmoidoscopy/Colonoscopy
  • 23. Site Distribution
  • 24. 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
  • 25. 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
  • 26. 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
  • 27. Future techniques for colorectal cancer screening • Stool DNA testing • Capsule endoscopy (Givens capsule) • CT colography (virtual colonoscopy)
  • 28. Videocapsule
  • 29. CT Colography Colon Polyp
  • 30. CT Colography Colon Polyp
  • 31. CT Colography Colon Cancer
  • 32. 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)
  • 33. 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).
  • 34. 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.
  • 35. 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
  • 36. 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
  • 37. 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
  • 38. 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
  • 39. 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.
  • 40. 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