February 28, 2011
Cancer Prevention Monday
According to the Centers for Disease Control (CDC), colorectal cancer kills at least 50,000 Americans each year and is the second leading cancer cause of death in the United States. More than 140,000 people in the U.S. are diagnosed with colorectal cancer each year.
“After lung cancer, for which smoking is the major risk factor, colon cancer is the one that we know the most about modifiable risk factors that may be targeted for prevention,” says Elizabeth Platz, ScD, MPH, a cancer epidemiologist at the Johns Hopkins Bloomberg School of Public Health.
Cancer of the large intestine (colon) and/or the rectum occurs in both men and women, primarily among those over the age of 50. The risk for developing colon cancer increases with age, family history, inflammatory bowel disease, and genetic syndromes. There is convincing evidence that many diet and lifestyle factors are associated with a higher risk of colorectal cancer as described in the joint report released by the American Institute for Cancer Research and the World Cancer Research Fund. These include:
- Red meat intake: Studies cite the potentially carcinogenic N-nitroso compounds, cooking meat at high temperatures, and the production of free radicals from heme iron as possible mechanisms for this association.
- Processed meat intake: Sodium nitrites, added as color fixatives and food preservatives to processed meats are particularly noted as potential mutagens and carcinogens.
- Body fatness, particularly abdominal fatness: Greater body fatness contributes to an increase in insulin resistance and an increase in inflammation, among other possible mechanisms.
- Alcohol intake: Higher alcohol intake, especially for those who do not take in enough folic acid (found in leafy green vegetables, citrus fruits, legumes, and whole grains) has been linked to colon cancer.
- Physical inactivity (all types): Colon cancer is the only cancer in which greater physical activity is convincingly associated with a lower rate. Physical activity not only reduces insulin resistance, but also increases bowel transit time.
In addition, the U.S. Surgeon General’s report says that evidence suggests the following association with colorectal cancer.
- Cigarette smoking: This has been particularly associated with those who smoked significant amounts during early adulthood, as it is related to the development of adenomatous polyps.
Beyond adjusting these modifiable behaviors, the United States Preventive Services Task Force also recommends colorectal screening for men and women between the ages of 50 and 75. Several types of screening tests for colorectal cancer exist, including a high-sensitivity FOBT (stool test), a flexible sigmoidoscopy, and a colonoscopy, and each can be used alone or in combination with the others. Each test varies in frequency, with a FOBT occurring every year, a sigmoidoscopy every 5 years, and a colonoscopy every 10 years. Those at high risk may require earlier and more frequent screenings than others. Speak with your doctor to determine which test(s) you should take and when you should begin.
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