Colorectal cancer

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Pathophysiology

Colorectal cancer probably arises from colorectal polyps.[1] Adenomatous polyps convert to cancers at a rate of about 1% per year.[2]

Treatment

Colorectal cancer treatment information from the National Cancer Institute's Physician Data Query


Medications

Cetuximab

Cetuximab, an IgG1 chimeric monoclonal antibody against epidermal growth factor receptor, may help according to a randomized controlled trial.[3]

Prognosis

5-Year Relative Survival Rates By Year Dx By Cancer Site All Ages, All Races, Both Sexes 1975-2000.

Staging information

Colorectal cancer staging information from the National Cancer Institute's Physician Data Query


Screening

For more information, see: colonic polyp.


Practice guidelines

A clinical practice guideline by the US Preventive Services Task Force has addressed colorectal cancer:[4]

  • "recommends screening for colorectal cancer using fecal occult blood testing, sigmoidoscopy, or colonoscopy in adults, beginning at age 50 years and continuing until age 75 years."
  • "recommends against routine screening for colorectal cancer in adults 76 to 85 years of age. There may be considerations that support colorectal cancer screening in an individual patient."
  • "recommends against screening for colorectal cancer in adults older than age 85 years"
  • "the evidence is insufficient to assess the benefits and harms of computed tomographic colonography and fecal DNA testing (a subsequent study found that DNA was more sensitive but less specific[5])"

A clinical practice guideline jointly written by the American Cancer Society and other groups recommends one of:[6]

  • Flexible sigmoidoscopy every 5 years
  • Barium enema every 5 years
  • Virtual colonography (a noninvasive test based on computed tomography) every 5 years
  • Colonoscopy every 10 years

When polyps are found, a clinical practice guideline jointly written by the American Cancer Society and other groups states:[7]

  • High risk polyps are 1) 3 or more synchronous adenomas, 2) adenomas ≥1 cm in diameter, or 3) villous histology or high-grade dysplasia.
  • High risk polyps should have follow-up colonoscopy in 3 years
  • Low risk polyps should have repeat colonoscopy in 5 to 10 years
  • If no adenomas are found, follow-up evaluation should be at 10 years

A validation of these guidelines found:[8]

  • High risk adenomas - 9% of an advanced adenoma at 4 years of follow-up.
  • Low risk adenomas - 5% of an advanced adenoma at 4 years of follow-up.

Evidence

Testing for fecal occult blood annually for 13 years can reduce colorectal cancer by 33%.[9] As 0.9% of subjects had cancer over 13 years, this indicated a number needed to screen of 339 patients (calculation).

Screening colonoscopy probably reduced the risk of death from colorectal cancer by 60 to 70%.[10][11] If 0.9% of subjects develop cancer, this indicates a number needed to screen of 161 patients (calculation).

Prevention

Aspirin chemoprophylaxis

A clinical practice guideline by the U.S. Preventive Services Task Force (USPSTF) recommended against taking aspirin (grade D recommendation).[12] The Task Force acknowledged that aspirin may reduce the incidence of colorectal cancer, but "concluded that harms outweigh the benefits of aspirin and NSAID use for the prevention of colorectal cancer". A subsequent meta-analysis concluded "300 mg or more of aspirin a day for about 5 years is effective in primary prevention of colorectal cancer in randomised controlled trials, with a latency of about 10 years".[13] However, long-term doses over 81 mg per day may increase bleeding events.[14]

Calcium

A meta-analysis by the Cochrane Collaboration of randomized controlled trials published through 2002 concluded "Although the evidence from two RCTs suggests that calcium supplementation might contribute to a moderate degree to the prevention of colorectal adenomatous polyps, this does not constitute sufficient evidence to recommend the general use of calcium supplements to prevent colorectal cancer.".[15] Subsequently, one randomized controlled trial by the Women's Health Initiative (WHI) reported negative results.[16] A second randomized controlled trial reported reduction in all cancers, but had insufficient colorectal cancers for analysis.[17]

References

  1. ↑ Levine JS, Ahnen DJ (December 2006). "Clinical practice. Adenomatous polyps of the colon". N. Engl. J. Med. 355 (24): 2551–7. DOI:10.1056/NEJMcp063038. PMID 17167138. Research Blogging.
  2. ↑ Stryker SJ, Wolff BG, Culp CE, Libbe SD, Ilstrup DM, MacCarty RL (November 1987). "Natural history of untreated colonic polyps". Gastroenterology 93 (5): 1009–13. PMID 3653628. [e]
  3. ↑ Jonker DJ, O'Callaghan CJ, Karapetis CS, et al (2007). "Cetuximab for the treatment of colorectal cancer". N. Engl. J. Med. 357 (20): 2040–8. DOI:10.1056/NEJMoa071834. PMID 18003960. Research Blogging.
  4. ↑ (October 2008) "Screening for Colorectal Cancer: U.S. Preventive Services Task Force Recommendation Statement". Annals of Internal Medicine. PMID 18838716. [e]
  5. ↑ Ahlquist DA, Sargent DJ, Loprinzi CL, et al (October 2008). "Stool DNA and occult blood testing for screen detection of colorectal neoplasia". Ann. Intern. Med. 149 (7): 441–50, W81. PMID 18838724. [e]
  6. ↑ Levin, B., Lieberman, D. A., McFarland, B., Smith, R. A., Brooks, D., Andrews, K. S., et al. (2008). Screening and surveillance for the early detection of colorectal cancer and adenomatous polyps, 2008: a joint guideline from the American Cancer Society, the US Multi-society Task Force on Colorectal Cancer, and the American College of Radiology. CA Cancer J Clin, CA.2007.0018. DOI:10.3322/CA.2007.0018.
  7. ↑ Winawer SJ, Zauber AG, Fletcher RH, et al (May 2006). "Guidelines for colonoscopy surveillance after polypectomy: a consensus update by the US Multi-Society Task Force on Colorectal Cancer and the American Cancer Society". Gastroenterology 130 (6): 1872–85. DOI:10.1053/j.gastro.2006.03.012. PMID 16697750. Research Blogging.
  8. ↑ Laiyemo AO, Murphy G, Albert PS, et al (March 2008). "Postpolypectomy colonoscopy surveillance guidelines: predictive accuracy for advanced adenoma at 4 years". Ann. Intern. Med. 148 (6): 419–26. PMID 18347350. [e]
  9. ↑ Mandel JS, Bond JH, Church TR, et al (May 1993). "Reducing mortality from colorectal cancer by screening for fecal occult blood. Minnesota Colon Cancer Control Study". N. Engl. J. Med. 328 (19): 1365–71. PMID 8474513. [e]
  10. ↑ Baxter NN, Goldwasser MA, Paszat LF, Saskin R, Urbach DR, Rabeneck L (January 2009). "Association of colonoscopy and death from colorectal cancer". Ann. Intern. Med. 150 (1): 1–8. PMID 19075198. [e]
  11. ↑ Ransohoff DF (January 2009). "How much does colonoscopy reduce colon cancer mortality?". Ann. Intern. Med. 150 (1): 50–2. PMID 19075200. [e]
  12. ↑ (2007) "Routine aspirin or nonsteroidal anti-inflammatory drugs for the primary prevention of colorectal cancer: U.S. Preventive Services Task Force recommendation statement". Ann. Intern. Med. 146 (5): 361-4. pmid=17339621. [e] PMID 17339621
  13. ↑ Flossmann E, Rothwell PM (2007). "Effect of aspirin on long-term risk of colorectal cancer: consistent evidence from randomised and observational studies". Lancet 369 (9573): 1603-13. DOI:10.1016/S0140-6736(07)60747-8. PMID 17499602. Research Blogging. PMID 17499602
  14. ↑ Campbell CL, Smyth S, Montalescot G, Steinhubl SR (2007). "Aspirin dose for the prevention of cardiovascular disease: a systematic review". JAMA 297 (18): 2018-24. DOI:10.1001/jama.297.18.2018. PMID 17488967. Research Blogging. PMID 17488967
  15. ↑ Weingarten MA, Zalmanovici A, Yaphe J (2005). "Dietary calcium supplementation for preventing colorectal cancer and adenomatous polyps". Cochrane database of systematic reviews (Online) (3): CD003548. DOI:10.1002/14651858.CD003548.pub3. PMID 16034903. Research Blogging.
  16. ↑ Wactawski-Wende J, Kotchen JM, Anderson GL, et al (2006). "Calcium plus vitamin D supplementation and the risk of colorectal cancer". N. Engl. J. Med. 354 (7): 684-96. DOI:10.1056/NEJMoa055222. PMID 16481636. Research Blogging.
  17. ↑ Lappe JM, Travers-Gustafson D, Davies KM, Recker RR, Heaney RP (2007). "Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial". Am. J. Clin. Nutr. 85 (6): 1586-91. PMID 17556697. [e]
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