Colorectal cancer primary prevention
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Editor(s)-in-Chief: C. Michael Gibson, M.S.,M.D. [1] Phone:617-632-7753; Elliot B. Tapper, M.D., Beth Israel Deaconess Medical Center
Overview
Prevention techniques
Surveillance
Most colorectal cancer arise from adenomatous polyps. These lesions can be detected and removed during colonoscopy. Studies show this procedure would decrease by > 80% the risk of cancer death, provided it is started by the age of 50, and repeated every 5 or 10 years.[1]
As per current guidelines under National Comprehensive Cancer Network, in average risk individuals with negative family history of colon cancer and personal history negative for adenomas or Inflammatory Bowel diseases, flexible sigmoidoscopy every 5 years with fecal occult blood testing annually or double contrast barium enema are other options acceptable for screening rather than colonoscopy every 10 years (which is currently the Gold-Standard of care).
Lifestyle & Nutrition
The comparison of colorectal cancer incidence in various countries strongly suggests that sedentarity, overeating (i.e., high caloric intake), and perhaps a diet high in meat (red or processed) could increase the risk of colorectal cancer. In contrast, a healthy body weight, physical fitness, and good nutrition decreases cancer risk in general. Accordingly, lifestyle changes could decrease the risk of colorectal cancer as much as 60-80%.[2]
A high intake of dietary fiber (from eating fruits, vegetables, cereals, and other high fiber food products) has, until recently, been thought to reduce the risk of colorectal cancer and adenoma. In the largest study ever to examine this theory (88,757 subjects tracked over 16 years), it has been found that a fiber rich diet does not reduce the risk of colon cancer. [3] A 2005 meta-analysis study further supports these findings.[4]
The Harvard School of Public Health states: "Health Effects of Eating Fiber: Long heralded as part of a healthy diet, fiber appears to reduce the risk of developing various conditions, including heart disease, diabetes, diverticular disease, and constipation. Despite what many people may think, however, fiber probably has little, if any effect on colon cancer risk." [5]
Chemoprevention
More than 200 agents, including the above cited phytochemicals, and other food components like calcium or folic acid (a B vitamin), and NSAIDs like aspirin, are able to decrease carcinogenesis in preclinical models: Some studies show full inhibition of carcinogen-induced tumours in the colon of rats. Other studies show strong inhibition of spontaneous intestinal polyps in mutated mice (Min mice). Chemoprevention clinical trials in human volunteers have shown smaller prevention, but few intervention studies have been completed today. Calcium, aspirin and celecoxib supplements, given for 3 to 5 years after the removal of a polyp, decreased the recurrence of polyps in volunteers (by 15-40%). The "chemoprevention database" shows the results of all published scientific studies of chemopreventive agents, in people and in animals.[6]
Aspirin chemoprophylaxis
Aspirin should not be taken routinely to prevent colorectal cancer, even in people with a family history of the disease, because the risk of bleeding and kidney failure from high dose aspirin (300mg or more) outweigh the possible benefits.[7]
A clinical practice guideline by the U.S. Preventive Services Task Force (USPSTF) recommended against taking aspirin (grade D recommendation).[8] 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".[9] However, long-term doses over 81 mg per day may increase bleeding events.[10]
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.".[11] Subsequently, one randomized controlled trial by the Women's Health Initiative (WHI) reported negative results.[12] A second randomized controlled trial reported reduction in all cancers, but had insufficient colorectal cancers for analysis.[13]
References
- ↑ Winawer SJ, Zauber AG, Ho MN, O'Brien MJ, Gottlieb LS, Sternberg SS, Waye JD, Schapiro M, Bond JH, Panish JF, Ackroyd F, Shike M, Kurtz RC, Hornsby-Lewis L, Gerdes H, Stewart ET, The National Polyp Study Workgroup. Prevention of colorectal cancer by colonoscopic polypectomy. N Engl J Med 1993;329:1977-81. PMID 8247072.
- ↑ Cummings, JH (1998). "Diet and the prevention of cancer". BMJ: 1636–40. PMID 9848907. Text "issue317" ignored (help); Unknown parameter
|coauthors=ignored (help) - ↑ "Dietary Fiber and the Risk of Colorectal Cancer and Adenoma in Women". New England Journal of Medicine (340): 169–76. 1999.
- ↑ "Dietary Fiber and Colorectal Cancer: An Ongoing Saga". Journal of the American Medical Association (294(22)): 2904–2906. 2005. PMID 16352792.
- ↑ "Health Effects of Eating Fiber".
- ↑ "Colorectal Cancer Prevention: Chemoprevention Database". Retrieved 2007-08-23.
- ↑ Agency for Healthcare Research and Quality (2007-03-05). "Task Force Recommends Against Use of Aspirin and Non-Steroidal Anti-Inflammatory Drugs to Prevent Colorectal Cancer". United States Department of Health & Human Services. Retrieved 2007-05-07.
- ↑ "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. 2007. pmid=17339621. PMID 17339621
- ↑ 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. PMID 17499602
- ↑ 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. PMID 17488967
- ↑ 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.
- ↑ 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.
- ↑ 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.