Colorectal cancer |

Colorectal Cancer Incidence, Location, Anatomy and Pathogenesis

 Jan 16, 2008 Viewed: 1383

Incidence and Location

The incidence of CRC increases with age and is highest during the eighth decade of life. Colorectal cancer has shown a gradual shift in location from left-sided to right-sided tumors over the past several decades. Rosato and Marks compared the distribution of CRC from 1939 to 1957 to that for a group of patients from 1970 to 1977. Percentages of cancers based on location for 1939 to 1957 and 1970 to 1977, respectively, have shifted as follows: rectum colon 51% versus 32%, sigmoid colon 13% versus 31%, descending colon 20% versus 5%, transverse colon 4% versus 13%, and ascending colon 12% versus 16%. In a prospective study, Tedesco et al. evaluated 642 patients and found that 66% of polyps and cancers were located within 60 cm of the anus, and that 5% of polyps and 28% of cancers were located within the first 25 cm. Knowledge of this shift from predominantly left-sided to right-sided tumors is an important consideration when discussing diagnostic studies.

Anatomy and Pathogenesis

The colon runs from the cecum to the rectum. Lymphatic drainage occurs in both a segmental and a circumferential fashion. This segmented drainage pattern explains why CRCs may appear as a localized, apple-core-type lesion. Histologically, normal colonic columnar epithelium is proliferative only in the lower two thirds of the glandular crypts. The upper one third and surface cells are normally nonproliferative. When exposed to carcinogens, mutational activation of oncogenes and the inactivation of tumor suppresser genes occur. At least four or five mutations are required to produce a malignant tumor. Cumulative mutations are responsible for the biologic properties of the tumor.

Exposure of normal colonic epithelium to carcinogens leads to the movement of proliferative cells from the basal two thirds of the crypts to the surface cell layer. These cells replicate but do not exfoliate, leading to increasing numbers of cells and eventual polyp formation. Polyps can be sessile (broad-based) or pedunculated (on a stalk), with the polyp’s histology being hyperplastic or neoplastic. If neoplastic, polyps are classified as adenomatous (tubular), villous (finger-like), or mixed (intermediate). Adenomatous polyps, if left untreated, may become progressively more dysplastic and eventually develop into carcinoma in situ or invasive CRC.

Colorectal cancer

Gregory L. Brotzman and Russell G. Robertson


References

  1. Greenlee RT, Hill-Harmon MB, Murray T, Thun M. Cancer statistics, 2001. CA Cancer J Clin 2001;51:15-36.
  2. Schrag D. Weeks J. Costs and cost-effectiveness of colorectal cancer prevention and therapy. Semin Oncol 1999;26:561-8.
  3. Fry R, Fleshman J, Kodner I. Cancer of colon and rectum. Clin Symp 1989;41:2-32.
  4. Sandler R, Lyles C, Peipins L, et al. Diet and risk of colorectal adenomas: macronutrients, cholesterol, and fiber. J Natl Cancer Inst 1993;85:884-91.
  5. Vargas P, Alberts D. Primary prevention of colorectal cancer through dietary modification. Cancer 1992;70:1229-35.
  6. Toribara N, Sleisenger M. Screening for colorectal cancer. N Engl J Med 1995;332:861-7.
  7. U.S. Preventive Services Task Force. Guide to clinical preventative services, 2nd ed. Baltimore: Williams & Wilkins, 1996.
  8. Bard J. Colorectal cancer update. Prevention, screening, treatment & surveillance for high risk groups. Med Clin North Am 2000;84:1163-79.
  9. Wayne M, Cath A, Pamies R. Colorectal cancer: a practical review for the primary care physician. Arch Fam Med 1995;4:357-66.
  10. Lieberman D, Smith F. Screening asymptomatic subjects for colon malignancy with colonoscopy. Am J Gastroenterol 1991;86:946-51.
  11. Sinnige H, Mulder N. Colorectal carcinoma: an update. Neth J Med 1991;38:217-28.
  12. Winawer S, Zauber A, Gerdes H, et al. Risk of colorectal cancer in the families of patients with adenomatous polyps. N Engl J Med 1996;334:82-7.
  13. Stryker S, Wolff B, Culp C, et al. Natural history of untreated colonic polyps. Gastroenterology 1987;93:1009-13.
  14. Pennazio M, Arrigoni A, Risio M, Spandre M, Rossini F. Small rectosigmoid polyps as markers of proximal neoplasms. Dis Colon Rectum 1993;36:1121-5.
  15. Peterson G, Boyd P. Gene tests and counseling for colorectal cancer risk: lessons from familial polyposis. J Natl Cancer Inst 1995;17:67-71.
  16. Alberts D, Ritenbaugh C, Story J, et al. Randomized, double-blinded, placebo-controlled study of effect of wheat bran fiber and calcium on fecal bile acids in patients with resected adenomatous colon polyps. J Natl Cancer Inst 1995;88:81-92.
  17. Terry P, Giovannucci E, Michels K, et al. Fruit, vegetables, dietary fiber, and risk of colorectal cancer. J Natl Cancer Inst 2001;93:525-33.
  18. Giovannucci E, Rimm E, Ascherio A, Stampfer M, Colditz G, Willett W. Alcohol, low-methionine-low-folate diets, and risk of colon cancer in men. J Natl Cancer Inst 1995;87:265-73.
  19. Levin K, Dozois R. Epidemiology of large bowel cancer. World J Surg 1991;15:562-7.
  20. Kune G, Vitetta L. Alcohol consumption and the etiology of colorectal cancer: a review of the scientific evidence from 1957 to 1991. Nutr Cancer 1992;18:97-111.
  21. Martinez M, McPherson S, Annegers J, Levin B. Cigarette smoking and alcohol consumption as risk factors for colorectal adenomatous polyps. J Natl Cancer Inst 1995;87:274-9.
  22. Levin B, Murphy G. Revision in American Cancer Society recommendations for the early detection of colorectal cancer. CA Cancer J Clin 1992;42:296-9.
  23. DeCosse J, Tsioulias G, Jacobson J. Colorectal cancer: detection, treatment and rehabilitation. CA Cancer J Clin 1994;44:27-42.
  24. Bachwich D, Lichtenstein G, Traber P. Cancer in inflammatory bowel disease. Med Clin North Am 1994;78:1399-412.
  25. Axtell L, Chiazze L. Changing relative frequency of cancers of the colon and rectum in the United States. Cancer 1966;19:750-4.
  26. Rosato F, Marks G. Changing site distribution patterns of colorectal cancer at Thomas Jefferson University Hospital. Dis Colon Rectum 1981;24:93-5.
  27. Tedesco F, Wayne J, Avella J, Villalobos M. Diagnostic implications of the spatial distribution of colonic mass lesions (polyps and cancers): a prospective colonoscopic study. Gastroenterol Endosc 1980;26:95-7.
  28. Cho K, Vogelstein B. Genetic alterations in the adenoma-carcinoma sequence. Cancer 1992;70:1727-31.
  29. Winawer SJ, Zauber AG, Ho MN, et al. Prevention of colorectal cancer by colonoscopic polypectomy. N Engl J Med 1993;329:1977-83.
  30. Tomeo CA, Colditz GA, Willet WC, et al. Harvard report on cancer prevention: vol. 3: prevention of colon cancer in the United States. Cancer Causes Control 1999;10:167-80.
  31. Screening for colorectal cancer - United States, 1997. MMWR 1999;48:116-21.
  32. Smith R, von Eschenback A, Wender R, Levin B, Byers T, et al. American Cancer Society guidelines for the early detection of cancer: update of early detection guidelines for prostate, colorectal, and endometrial cancers and Update 2001: testing for early lung cancer detection. CA Cancer J Clin 2001;51:38-75.
  33. Simon J. Occult blood screening for colorectal carcinoma: a critical review. Gastroenterology 1985;88:820-37.
  34. Van Dam J, Bond J, Sivak M. Fecal occult blood screening for colorectal cancer. Arch Intern Med 1995;155:2389-402.
  35. Mandel J, Bond J, Church T, et al. Reducing mortality from colorectal cancer by screening for fecal occult blood. N Engl J Med 1993;328:1365-71.
  36. Freedman S. The role of barium enema in detecting colorectal disease: a radiologist's perspective. Postgrad Med 1992;92:245-51.
  37. Selby J, Friedman G, Quesenberry C, Weiss N. A case-control study of screening sigmoidoscopy and mortality from colorectal cancer. N Engl J Med 1992;326:653-7.
  38. Lieberman D, Weiss D, Bond J, Ahnen D, Garewal H, Chejfec G. Use of colonoscopy to screen asymptomatic adults for colorectal cancer. N Engl J Med 2000;343:162-8.
  39. Imperiale TF, Wagner DR, Lin CY, et al. Risk of advanced proximal neoplasms in asymptomatic adults according to the distal colorectal findings. N Engl J Med 2000;343:169-74.
  40. Varma J, Pfenninger J. Flexible sigmoidoscopy. In: Pfenninger J, Fowler G, eds. Procedures for primary care physicians. St. Louis: Mosby, 1994;907-27.
  41. Barthel J, Hinojosa T, Shah N. Colonoscope length and procedure efficiency. J Clin Gastroenterol 1995;21:30-2.
  42. Johnson CD, Dachman AH. CT colonography: the next colon screening examination? Radiology 2000;216(2):331-41.
  43. Deans G, Parks T, Rowlands B, Spence R. Prognostic factors in colorectal cancer. Br J Surg 1992;79:608-13.
  44. Kronborg O. Staging and surgery for colorectal cancer. Eur J Cancer 1993;29A:575-83.
  45. Nelson H, Petrelli N, Carlin A, et al. Guidelines 2000 for colon and rectal surgery. J Natl Cancer Inst 2001;93:583-96.
  46. Abdalla E, Blair E, Jones R, Sue-Ling H, Johnston D. Mechanism of synergy of levamisole and fluorouracil: induction of human leukocyte antigen class I in colorectal cancer cell line. J Natl Cancer Inst 1995;87:489-96.
  47. Connell MJ, Mailliard JA, Kahn MJ, et al. Controlled trial of fluorouracil and low-dose leucovorin given for 6 months as postoperative adjuvant therapy for colon cancer. J Clin Oncol 1997;15:246.
  48. Verschraegen C, Pazdur R. Medical management of colorectal carcinomas. Tumor 1994;80:1-11.
  49. Winawer S, St. John D, Bond J, et al. Prevention of colorectal cancer: guidelines based on new data. WHO Bull OMS 1995;73:7-10.
  50. Janne P, Mayer J. Chemoprevention of colorectal cancer. N Engl J Med 2000;342:1960-8.

Provided by ArmMed Media