Switching from a “Western” diet with lots of fat and meat to a fiber-rich diet for just two weeks makes conditions in the large intestine less favorable to the development of colon cancer. The opposite switch may promote the formation of cancer. That’s the conclusion from a small but elegant study done in urban Pittsburgh and rural KwaZulu-Natal, South Africa. In the study, 20 volunteers from each area switched diets. For two weeks, the Americans ate a traditional high-fiber African diet rich in fruits, vegetables, nuts, and beans, while the Africans ate a Western diet with more fat, protein, and meat. In just two weeks, significant changes occurred in the lining of the colon and in its chemical and bacterial make-up in both groups, but in different directions. Those following the African diet showed improvements in colon health likely to protect against colon cancer, while those following the Western diet showed changes that could lead to colon cancer.
Looking for ways to ward off colorectal cancer? According to a new study, a pescovegetarian diet — that’s a vegetarian diet that includes fish — was linked to a 43% reduction in the risk of developing colorectal cancer. The study, published in JAMA Internal Medicine, adds more support to the notion that something in red meat, or the way it is cooked, encourages the growth of colorectal cancer. It’s also possible that eating more plant foods provides extra beneficial nutrients such as folate, calcium, and fiber that may protect against colorectal cancer. Fish contain healthful omega-3 fats and vitamin D. Another good strategy for preventing harm from colorectal cancer, the second leading cause of cancer death in the United States? Have colonoscopies as needed.
Some good news on the cancer front: between 2000 and 2010, rates of colorectal cancer in American adults fell by about one-third. That decline mirrored a sharp rise in colorectal cancer testing during the same period. American Cancer Society researchers found that the drop in colorectal cancer rates was highest among Americans aged 65 years and older. Cases fell 3.6% a year from 2001 to 2008, then dropped even more by 7.2% a year from 2008 to 2010. But the researchers saw a troubling trend in younger adults: an increase in colorectal cancer of 1.1% a year among people under age 50. Rising obesity rates may be to blame. The researchers attribute the decline in colorectal cancer to early testing for the disease. Despite the optimistic findings, colorectal cancer is still a scourge. In the U.S. this year, an estimated 72,000 men and 65,000 women will be diagnosed with colorectal cancer; 26,000 men and 24,000 women will die of it.
Checking seemingly healthy people for cancer—what doctors call screening—seems like a simple process: Perform a test and either find cancer early and cure it or don’t find it and breathe easy. It works for colon, breast, and cervical cancers, but not for others. For colon cancer, there are several effective screening tests: colonoscopy, sigmoidoscopy, and stool testing. Two new studies in yesterday’s New England Journal of Medicine help further quantify their benefits. In the studies, all three types of test reduced the risk of developing or dying from colon cancer. Colonoscopy worked best, followed by sigmoidoscopy and then stool testing. The biggest challenge for colon cancer screening is getting people to have the available tests. About 50,000 Americans die of colon cancer each year—many of these can be prevented with early screening.
Back in 2009, Dr. Andrew T. Chan and his colleagues at Harvard-affiliated Massachusetts General Hospital found that people diagnosed with colorectal cancer who took aspirin on a regular basis tended to live longer than those who didn’t take aspirin. Aspirin worked only for some people, though, so Chan and a larger team of researchers set out to learn why. Their latest work, published in the New England Journal of Medicine, indicates that people with colorectal cancer who have a mutation in a gene called PIK3CA are most likely to benefit from aspirin. (About 15% to 20% of people with colorectal cancer have this gene mutation.) The mutation permits colon cancer cells to thrive. Aspirin blocks this action. If confirmed, this work could lead to routine genetic testing for people with this common cancer, and aspirin therapy for those with the PIK3CA mutation.
Surviving cancer was once a challenging achievement. Today, more than 12 million Americans are cancer survivors, and many live long after their diagnoses. New guidelines from the American Cancer Society (ACS) offer them science-based advice for eating better and staying active—two keys to healthy living for cancer survivors and everyone else. The report, called Nutrition and Physical Activity Guidelines for Cancer Survivors, is available for free from the ACS website. The guidelines provide specific advice for survivors of a variety of major cancers: prostate, colorectal, lung, breast, ovarian, endometrial, upper GI, head and neck, and hematologic. They urge cancer survivors to maintain a healthy weight, avoid inactivity and return to normal daily activities as soon as possible following diagnosis, eventually aim to exercise at least 150 minutes per week, and follow an eating pattern that is rich in vegetables, fruits, and whole grains.