More than 130,000 men and women are told they have colon or rectal cancer every year, making it the third most commonly diagnosed cancer, according to the American Cancer Society.
But a new report from the American Institute for Cancer Research and the World Cancer Research Fund provides new evidence that the right eating and exercise plan can really help lower your risk of developing the disease.
In the report, researchers analyzed 99 studies with data on 29 million people.
“The findings are clear that diet and lifestyle play a major role,” says lead author Edward L. Giovannucci, M.D., Sc.D., professor of nutrition and epidemiology at the Harvard TH Chan School of Public Health. “Despite its prevalence, colorectal cancer is a highly preventable disease.”
Foods To Eat More Of
It’s long been suspected that eating more whole grains will reduce your risk of colon cancer, but this is the first time that it has been confirmed.
“Until recently, there had not been many studies that directly examined whole grain intake and subsequent colorectal cancer risk in large populations,” says Giovannucci. “But now we have enough research to say the link has strong evidence.”
In fact, eating about three servings of whole grains a day can lower colorectal cancer risk by 17 percent. (One serving is equal to 1 cup of ready-to-eat cereal, a slice of bread, or ½ cup of cooked rice or pasta.)
Why do whole grains help?
“Fiber is one of the keys to prevention of colon cancer,” says Michael A. Valente, M.D., a colorectal surgeon at the Cleveland Clinic, who was not involved in the AICR/WCRF report. “But we suspect that it’s really the thousands of nutrients, minerals, and other natural chemical compounds present in foods that are high in fiber—such as whole grains and fruits and vegetables—that are helping to prevent cancer, not just the fiber itself.”
Many of these compounds have what the report called “plausible anti-carcinogenic properties.” Which is why, in addition to eating more whole grains, it’s smart to increase consumption of fiber-rich fruits and vegetables as well.
Foods To Cut Back On
The researchers found that eating a lot of red meat (such as beef and pork) and processed meat (such as bacon, cold cuts, and sausage) were potentially harmful.
Every 1.8 ounces a day of processed meat increased risk by as much as 16 percent, while eating more than about 17½ ounces of red meat a week was labeled a “probable cause” of colorectal cancer.
One theory as to why these meats increase colon cancer risk is that they have high levels of iron derived from blood, which has been shown to promote the growth of colorectal tumors.
The connection between alcohol and colorectal cancer was also “convincing,” according to the report, and was especially strong for those who drink more than 30 grams per day (the equivalent of about two glasses of wine, or two cocktails or two beers).
“If you do consume alcohol, keep your intake moderate,” recommends Giovannucci.
Other Steps You Can Take
Getting more whole grains and veggies, and less meat may have another risk-reducing benefit: helping you to maintain a healthy weight. According to the report, there is strong, convincing evidence that people who are overweight are more likely to develop colon cancer.
All types of physical activity—not just formal exercise—was protective, too, with the most active people having about 20 percent lower risk of colon (but not rectal) cancer than the least active.
The report did not cover screening for colon cancer, but it’s a preventive move that deserves mention, and detailed below. Colorectal cancer usually develops over 10 to 15 years without causing symptoms. Most cases start as noncancerous polyps in the lining of the large intestine or the rectum. Detecting and removing polyps prevents them from developing into cancer.
You should have a colonoscopy every five to 10 years staring at age 50.
And if you have a close relative who had colorectal cancer, you should be even more vigilant about changing your lifestyle and getting regular screenings.
“Having a first-degree relative (mother, father, sibling) with the disease increases your risk by nearly 100 percent compared to the average person,” says N. Jewel Samadder, M.D., a gastroenterologist at the Mayo Clinic and expert with the American Gastroenterological Association.
If that’s you, experts recommend that, in addition to improving your diet, weight, and activity level, you start getting colonoscopies at age 40.
Can a Daily Aspirin add to Prevention of Colon Cancer?
New guidelines suggest aspirin can prevent some forms of cancer, but taking one isn’t a good idea for everyone
A recent analysis by the U.S. Preventive Services Task Force suggests that aspirin might lower your risk of certain cancers, especially colon cancer if it’s taken long term. But you shouldn’t take aspirin for cancer prevention alone. That’s because the drug also poses risks—in particular the risk of dangerous bleeding in the stomach and brain—that may outweigh its possible protective effect against cancer.
But if you and your doctor decide that taking a daily, low-dose aspirin (81 mg, or a “baby aspirin”) is a good way to reduce your risk of heart disease, then think of a reduced risk of colon cancer as a bonus.
Considerable research going back decades shows that taking low-dose aspirin can help prevent heart attacks and ischemic strokes (the kind caused by blood clots) in people at high risk for cardiovascular disease. Now, researchers at the Preventive Services Task Force, an independent, volunteer panel of experts in prevention and evidenced-based medicine, have looked back at those studies to see what effect aspirin might have had on the risk of cancer. Combined data from three large studies involving 47,464 people suggested that, compared to people who didn’t take aspirin, those who did reduced their risk of colon cancer by about 40 percent, but only 10 to 19 years after they started taking the drug.
Uncertain Benefits vs. Known Harms
Encouraging results make a compelling case for ongoing, high-quality research looking at various cancers, but current evidence doesn’t support taking aspirin solely to prevent colon cancer. The evidence to date has to be interpreted cautiously, because it comes largely from a small set of older trials on cardiovascular disease prevention that were not set up to study the effect of aspirin on cancer. As a result, one cannot issue a blanket recommendation for the use of aspirin specifically for prevention of any cancers.
EARLY DETECTION OF CANCER: WHAT YOU NEED TO KNOW
Been putting off that colonoscopy? A new review evaluates the other screening options.
Colonoscopy has long been touted as the gold standard for colon cancer screening, recommended for all adults starting at age 50. With colon cancer expected to kill more than 49,000 Americans this year, getting a colonoscopy is currently the best way to reduce your risk. But, many people avoid colonoscopy because it includes an unpleasant 12-hour prep that includes drinking copious amounts of laxative and many trips to the bathroom, followed by the procedure itself, which costly and typically requires anesthesia.
Instead, consumers may want to opt for one of the two at-home colon-cancer screening tests available by prescription.
A new review published in JAMA by David Lieberman, M.D., professor of medicine and chief of gastroenterology at Oregon Health and Science University in Portland, concludes that home tests may be a decent first-step screener—although patients still need a colonoscopy if the kits find a worrisome result. What’s more, the kits can miss polyps, including precancerous growths that a doctor can spot and remove at the time of the colonoscopy.
FIT Test (Fecal Immunochemical Test)
The second most commonly prescribed colon-cancer screening test in the U.S. after colonoscopies, FIT tests have been in use for about 10 years.
The FIT test requires sending a single small fecal sample to a lab, which is then tested for blood. It’s a test that should be repeated annually, unlike colonoscopy, which is typically required just once every 10 years.
A person may have a cancer that isn’t bleeding at the time of the test, but that same tumor may bleed and be detected when the person is retested the following year. Research shows that this type of test detects cancer with 79 percent accuracy. But about five percent of tests deliver “false positive” results—which result in patients having to go for follow-up colonoscopies.
Multitarget Stool DNA Test
This test goes by the brand name Cologuard. It requires shipping an entire bowel movement to the lab. In addition to testing for blood, Cologuard looks for DNA from cancer cells scraped from the intestinal wall by feces as it passes through.
Studies have shown that this type of test detects cancer with 92 percent accuracy. However, 14 percent of tests deliver false positive results—far higher than the FIT test.
Another concern with this test is its sheer newness. Because Cologuard only received Food and Drug Administration approval in 2014, there are no studies showing that people who choose this screening method avoid dying of colon cancer in the long-term.
Studies also have not yet established the appropriate interval between testing, though the U.S. Preventive Services Task Force (USPSTF), an independent panel of health experts that advises the government, recommends repeating the test every one or three years.
BOTTOM LINE FOR SCREENING
If you have a personal or family history of colon cancer, then regular colonoscopies clearly are the best choice. For the rest of us, the best approach is less clear, but until more research data are available, colonoscopy (sadly) is still the safest route.
Sorry to disappoint!