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  • 4
  • 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 Bruce D. Greenwald, MD Associate Professor of Medicine University of Maryland School of Medicine
  • 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. 2003 Estimated US Cancer Cases* ONS=Other nervous system. * Excludes basal and squamous cell skin cancers and in situ carcinomas except urinary bladder. Source: American Cancer Society, 2003. Men 675,300 Women 658,800 210,816 Breast 79,056 Lung/bronchus 72,468 Colon & rectum 39,528 Uterine corpus 26,352 Ovary 26,352 Non-Hodgkin lymphoma 19,764 Melanoma of skin 19,764 Thyroid 13,176 Pancreas 13,176 Urinary bladder 62,238 All other sites Prostate 222,849 Lung/bronchus 94,542 Colon/rectum 74,283 Urinary bladder 40,518 Melanoma of 27,012 skin Non-Hodgkin 27,012 lymphoma Kidney 20,259 Oral cavity 20,259 Leukemia 20,259 Pancreas 13,506 All other sites 114,801 Men 675,300 Women 658,800
  • 5. 2003 Estimated US Cancer Deaths* ONS=Other nervous system. * Excludes basal and squamous cell skin cancers and in situ carcinomas except urinary bladder. Source: American Cancer Society, 2003. Men 285,900 Women 270,600 67,650 Lung/bronchus 40,590 Breast 29,766 Colon & rectum 16,236 Pancreas 13,530 Ovary 10,824 Non-Hodgkin lymphoma 10,824 Leukemia 8,118 Uterine corpus 5,412 Brain/ONS 5,412 Multiple myeloma 62,238 All other sites Lung/bronchus 88,629 Prostate 28,590 Colon & rectum 28,590 Pancreas 14,295 Non-Hodgkin 11,436 lymphoma Leukemia 11,436 Esophagus 11,436 Liver/intrahepatic 8,577 bile duct Urinary bladder 8,577 Kidney 8,577 All other sites 62,898
  • 6. Ethnic/Gender Differences Source: Surveillance, Epidemiology, and End Results Program, 1973-1999, Division of Cancer Control and Population Sciences, National Cancer Institute, 2002. African-American White
  • 7. Colon cancer rates for Baltimore City and Maryland, 1994-1998 Source: Maryland Department of Health and Mental Hygience. Annual Cancer Report. September, 2001. Age-adjusted incidence per 100,000 population
  • 8. How Does Colorectal Cancer Develop? Janne PA, Mayer RJ. N Engl J Med 2000;342:1960.
  • 9. Colon Polyp
  • 10. Colon Cancer
  • 11. How Does Colorectal Cancer Develop? Janne PA, Mayer RJ. N Engl J Med 2000;342:1960.
  • 12. Symptoms of Colorectal Cancer Fatigue Anemia Abdominal pain Rectal bleeding Change in bowel habits None Symptoms Findings Time Course Weight loss Abdominal mass Bowel obstruction Late Rectal mass Blood in stool Mid None Occult blood in stool Early
  • 13. Staging of Colorectal Cancer
  • 14. Frequency of Colorectal Cancer by Dukes Stage
  • 15. Survival by Dukes Stage
  • 16. Treatment of Colorectal Cancer by Stage
  • 17. Is Colorectal Cancer Preventable?
    • YES!
    • Screening
    • Chemoprevention
  • 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!!!
    • Mortality Test Reduction
    • Fecal occult blood testing 33%
    • Flexible sigmoidoscopy 66%
    • (in portion of colon examined)
    • FOBT + flexible sigmoidoscopy 43%
    • (compared to sigmoidoscopy alone)
    • Colonoscopy ~76-90%
    • (after initial screening and polypectomy)
  • 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. Why aren’t more people screened for colon cancer?
    • Reasons for refusal of fecal occult blood testing
      • Fear of further testing and surgery
      • Feeling well
      • Unpleasantness of stool collection procedure
    • But:
      • Strongest predictor of whether a patient will be screened = physician encouragement
    Hynam et al. J Epidemiol Comm Health 1995;49:84 Mandelson et al. Am J Prevent Med 2000;19:149
  • 22. 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. FOBT improves survival Years after diagnosis
  • 24. Trends in FOBT, 1997-2001 Source: Behavioral Risk Factor Surveillance System, 1996-1997, 1999, 2001, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention and Prevention, 1999, 2000, 2002.
  • 25. Double-contrast Barium Enema
  • 26. 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
  • 27. Sigmoidoscopy/Colonoscopy
  • 28. Site Distribution
  • 29. 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 Stewart et al Aust NZ J Surg 1999; 69:2 Newcomb et al. JNCI 1992; 84:1572 Painter et al Endoscopy 1999; 3:269 Rex et al. Gastrointest Endosc 1999; 99:727
  • 30. 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
  • 31. Colonoscopy
  • 32. Chemopreventive agents Effective, but has other problems Estrogen Effective Calcium Effective if obtained in diet Folate Not effective Vitamin E, vitamin C, beta carotene Probably effective NSAIDs (ibuprofen, etc) May be effective Aspirin Not effective Fiber
  • 33. Future techniques for colorectal cancer screening
    • Stool DNA testing
    • Capsule endoscopy (Givens capsule)
    • CT colography (virtual colonoscopy)
  • 34. Fecal Testing for Gene Mutations
  • 35. Fecal Testing for Gene Mutations
    • Pros
      • No sedation or preparation necessary
      • Home-based (sample mailed to physician)
      • No risk
    • Cons
      • Current tests not very good (~50% of cancers missed)
      • Cost
      • Frequency of exam unknown
      • Not therapeutic
      • Not covered by insurance
  • 36. Videocapsule
  • 37. Videocapsule Lymphoma
  • 38. CT Colography Colon Polyp
  • 39. CT Colography Colon Polyp
  • 40. CT Colography Colon Cancer
  • 41. CT Colography
    • Pros
      • No sedation necessary
      • 20 min procedure vs. 25 min for colonoscopy
      • Low risk
      • Extracolonic lesions may be detected
    • Cons
      • Preparation (residual fluid cannot be aspirated)
      • Air insufflation
      • Cost (? need for more frequent exams)
      • Radiation dose (similar to barium enema)
      • Not therapeutic
      • Not covered by insurance
  • 42. Summary
    • Colorectal cancer is the third most common cancer and cause of cancer death in the U.S.
    • Chemopreventive agents have modest benefit in average risk individuals
    • Screening for colorectal cancer saves lives!
    • Patient and physician compliance with screening is poor