Experts Answer Questions about Colon Cancer

• (Dr. David S. Alberts, M.D.)
  • I don't have a strong family history of cancer. Am I still at risk?
• (Dr. Andrew Weil, M.D.)
  • Why is seafood so much better for you than red meat?
• (Dr. Bernard Levin, M.D.)
  • What can you tell me about virtual colonoscopies? Can I get that screening instead of a traditional colonoscopy?
• (Dr. Walter Willett, M.D.)
  • Does being overweight raise my risk for colon cancer? What's the connection?

The Role of Family History

I don't have a strong family history of cancer. Am I still at risk?

The average person in the U.S. has a lifetime risk of nearly 40 percent of developing some type of cancer. So you're definitely at risk, says David S. Alberts, M.D., director of the Arizona Cancer Center in Tucson. All of us are at risk. But interestingly, lifestyle-not family history-is responsible for the majority of cancers in this country, Dr. Alberts says. More than 80 percent of all cancers are related to our diets, our smoking habits, our inactivity, and other preventable lifestyle factors.

The best overall strategy for lowering your risk? Dr. Alberts' Rx: Don't smoke, eliminate your exposure to secondhand smoke, stick to a diet that's low in fat with loads of fruits and vegetables, get physically active for at least 60 minutes every day, and follow all standard screening guidelines.

Extra credit: Limit your alcohol consumption. According to the American Cancer Society, the more alcohol you drink, the higher your risk of developing certain kinds of cancer, including oral, liver, and breast cancers. Although in moderation (no more than two drinks a day for men and one drink per day for women), alcohol may decrease your risk of heart disease and stroke (and, red wines may reduce cancer risk).

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The Role of Diet

Why is seafood so much better for you than red meat?

Both fish and meat are good sources of protein, but fish is the more healthful choice, says Andrew Weil, M.D., founder and director of the Program in Integrative Medicine at the University of Arizona's College of Medicine. The reason is the fat content.

Most protein contains fat, which can be pro-inflammatory (omega-6 fatty acids found in red meats and chicken) or anti-inflammatory (the omega-3's found in oily fish). And inflammation is a contributing factor in the development of many chronic diseases, including cancer. An added strike: The fat in meat is mostly saturated, which increases your risk of heart disease by influencing your cholesterol levels.

In fact, the two diets most associated with longevity are the traditional Japanese diet and the Mediterranean diet, both of which are plentiful in fish and omega-3s. "In my own diet, I include wild Alaskan salmon, Alaskan black cod, and sardines," says Dr. Weil, adding that, because hotter and longer cooking times produce a higher concentration of carcinogens, baking, broiling, and steaming are best. "Fans of grilling would do well to precook their protein in an oven or on the stove, and then grill for only a few minutes as a finishing touch," he says.

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Tell me about Virtual Colonoscopies

What can you tell me about virtual colonoscopies? Can I get that screening instead of a traditional colonoscopy?

"Virtual" colonoscopy simply means the use of computed tomography (CAT scan) to check the colon and bowel for polyps, diverticulosis, and cancer. The technology appeals to people who shudder-and who doesn't?-at the thought of conventional colonoscopy, which requires inserting a long, flexible, decidedly non-virtual scope with a tiny camera into the rectum and guiding it through the colon.

Both procedures require "bowel prep," meaning you'll have to take laxatives to clean out the colon beforehand. The upside: Unlike conventional colonoscopy, virtual colonoscopy doesn't require pain meds or sedatives and takes less time. If something suspicious is detected virtually, a follow-up conventional colonoscopy is required.

The down: Virtual colonoscopy is relatively new, which means it isn't yet widely available and insurers generally don't reimburse for it as a screening tool, says Bernard Levin, M.D., professor emeritus at University of Texas M.D. Anderson Cancer Center in Houston. Also important: The scan requires specialized training to read. "So it isn't a good test to take unless you have a radiologist who is proficient in the technology," says Dr. Levin.

That said, screening for colorectal cancer-which often has no symptoms-absolutely saves lives. When caught early, the 5-year survival rate is greater than 90 percent. Beginning at age 50, people who are at average risk for colorectal cancer should be screened either virtually or conventionally. People with a family history should be screened earlier. Discuss your health history with your doctor to decide the best way to proceed for you.

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The Role of Weight

Does being overweight raise my risk for colon cancer? What's the connection?

The evidence is clear: Being overweight or obese absolutely boosts your risk of colon cancer, says Walter Willett, M.D., professor of epidemiology and nutrition at the Harvard School of Public Health in Boston and co-author of Eat, Drink, and Weigh Less. The increased risk is somewhat greater for men than for women. Research shows that being mildly overweight, with a Body Mass Index (BMI) of 25 to 30, increases risk by about 20 percent in men and 10 percent in women. Being obese (BMI of 30 or more) raises risk by about 60 percent in men and 30 percent in women.

So the association between excess weight and cancer is very clear-but the reason behind it isn't. Most likely, says Dr. Willett, it's related to the higher insulin levels caused by extra body fat. But research has yet to prove as much.

The bottom line: If you're overweight or obese, losing weight will likely reverse your cancer risk. However, prevention-maintaining your weight, eating a healthful, low-fat, fiber-rich diet, staying active, and getting screened-is still and always the best approach.

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