Aside from getting a colonoscopy at age 50, or actively participating in another accepted form of colon cancer screening, you may be wondering what else can be done to prevent or reduce the risk of colorectal cancer (CRC). Fortunately, in addition to colon cancer screening, there are a few other ways to reduce the risk of CRC. Many of these strategies also limit the risk of developing heart disease.
Scientific data shows that regular exercise reduces the risk of developing colon cancer and colon polyps while physical inactivity may increase it. Several observational studies have shown a 25% reduction in colon cancer with 30 minutes or more of moderate to vigorous physical activity at least 4 days per week.
A diet that is high in fiber (such as fruits, vegetables) may offer some degree of protection from developing colorectal cancer. However, the degree to which dietary fiber intake reduces the development of adenomas or CRC is uncertain since the results of studies have been conflicting. Similarly, reducing consumption of red meat, animal fats, and foods that have been processed, salted, smoked, or cured may have beneficial effects. For those who choose to consume red meat in their diet, choosing lean cuts, and limiting intake to two four-ounce portions per week may be a reasonable compromise.
While smoking is well-known to increase the risk of many health concerns, including heart disease and lung cancer, studies show it also increases the risk of CRC. Cigarette use is responsible for approximately 20% of CRC cases in the U.S. The individuals at greatest risk are those with a twenty-pack year history of smoking (i.e., smoking 1 pack for 20 years). In these individuals, the risk of developing pre-cancerous polyps is 2-3x greater than non-smokers.
Individuals who drink more than 3 drinks per day may have a 20 – 50% higher risk of CRC development than those who only have an occasional drink. This finding may be partly explained by the protective effects of folic acid, and a higher likelihood of folic acid deficiency in those who drink significant amounts of alcohol. If you do drink alcohol, it’s best to do it in moderation (limit intake to 1 drink per day for women and 2 drinks per day for men).
The relative risk of developing adenomas and advanced adenomas (polyps >1 cm or with advanced histologic features) is twice as high in obese individuals. Those who are overweight as defined by a body mass index (BMI) of 25-29, and those who are obese (BMI 30 or >) may have a 1.5 to 2.8x increase in CRC compared with individuals who have a healthy BMI (18.5-24.9).
There is limited data supporting the benefits of vitamin B6, calcium with vitamin D, and folate or folic acid. A modest association between vitamin B6 intake and a decrease in CRC has been suggested in available data. Consuming the recommended daily allowances of calcium and vitamin D may have protective effects against CRC Talk to your doctor about recommended intake.
A substantial amount of evidence has shown that aspirin and NSAIDs are protective against the development of colonic adenomas and CRC. Routine use of aspirin and NSAIDs may reduce the development of colonic adenomas and CRC by 20-40%. However, the risks of routine use of aspirin or NSAIDs is not recommended given the increased risk for bleeding associated with these medications. If aspirin is already being used for its cardioprotective effects, there may be an added bonus of reducing the risk of CRC. Regular use of NSAIDs is only recommended in those individuals with a very high risk of developing colonic adenomas and colon cancer (i.e., Lynch syndrome and familial adenomatous polyposis, FAP).
While the majority of colon polyps and CRCs develop sporadically, approximately 20% of CRCs may be the result of a hereditary/genetic component. The lifetime risk of developing colon cancer is 6% and is roughly doubled in those with a single 1st degree relative with CRC (parent, sibling, or children). Familiarization with your family history of colon polyps and CRC is crucial in determining your individual risk of colon cancer. Your family history also plays a role in determining the appropriate interval between colonoscopic examinations.
In summary, the best way to reduce your risk of developing CRC is to follow the recommended guidelines for colon cancer screening. Colonoscopy is the preferred method of screening for colon cancer prevention, since it is the only modality that allows both identification and removal of precancerous colon polyps with a single exam. In addition to the recommended methods of colon cancer screening, the above measures may serve as a useful adjuncts to reduce the risk of developing colon polyps and colon cancer.
References:
1. Rex DK, Johnson DA, Anderson JC et al. American College of Gastroenterology Guidelines for Colorectal Cancer Screening. Am J Gastroenterol 2009;104:739-750.