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It's dietary advice that we know can help prevent colon cancer: Eat less meat and fewer fatty foods and skip sugary desserts.

According to a study published today in the Journal of the American Medical Association, it's also advice that can keep the cancer from recurring.

Colorectal cancer is the second leading cause of death from cancer among Canadians. While many studies have explored the link between foods and colon cancer prevention, very few have assessed the impact of diet on colon cancer recurrence and survival.

In the study, researchers from the Dana-Farber Cancer Institute in Boston examined the influence of certain eating patterns on colon cancer recurrence in 1,009 patients diagnosed with stage III colon cancer (cancer present in the colon and the lymph nodes).

Participants were drawn from a clinical trial investigating post-operative chemotherapy in addition to other treatment.

The researchers examined the impact of two dietary patterns on cancer recurrence and survival: a "Western" diet, with higher intakes of red and processed meats, sweets, fatty foods and refined grains, and a "prudent" diet, with more fruit, vegetables, legumes, fish, poultry and whole grains.

Patients reported their food intake during post-operative chemotherapy and six months afterward, and were then followed up for cancer recurrence or death for 5.3 years.

Among those who adhered to a Western eating pattern, patients with the highest intakes of these types of foods were three times more likely to have their cancer return or to die than those who ate less of those foods.

In contrast, the prudent eating pattern was not significantly related to cancer recurrence or survival.

These findings suggest that when it comes to improving colon cancer survival, it's actually what you don't eat that matters. Reducing consumption of red meat, fatty foods, sugary desserts and refined grains is an additional step that colon cancer patients can take to improve their outcome.

It's not boosting fruit and vegetable intakes that makes a difference, but rather eating less of so-called Western foods.

The researchers hypothesized that, following surgery for stage III colon cancer, eating the combination of foods typical of a Western diet could allow residual microscopic cancer to proliferate and spread.

Previous studies have linked a Western diet to a greater risk of developing colon cancer in the first place. Scientists suspect some foods or food components may work together to increase that risk. Western dietary patterns have been linked with higher levels of insulin and inflammatory compounds in the body, factors that may enhance tumour growth.

Studies that have focused on single foods or nutrients suggest that red meat, processed meat, animal fat, sugary foods, refined grains and alcohol increase colon cancer risk, while whole grains, calcium, vitamin D and folic acid lower the risk.

Diet isn't the only factor. Regular exercise has been shown to reduce the risk of colon cancer by 30 to 40 per cent. It's thought to do so by lowering levels of insulin and certain hormones that may promote cancer growth.

Research also suggests that regular activity - the equivalent of walking six or more days a week at two to 2.9 miles an hour - can halve the risk of dying from colon cancer.

Leslie Beck, a Toronto-based

dietitian at the Medcan Clinic,

is on CTV's Canada AM every Wednesday.

Reducing the initial risk

According to the Canadian Cancer Statistics 2007 report, 20,800 people will be diagnosed with colorectal cancer this year. While few studies have looked at diet and colon cancer recurrence, more is known about foods that may reduce your risk of initially developing the disease. The following strategies may help.

Cut down on meat

Many studies show that people who eat the most red meat (beef, veal, pork, lamb) and/or processed meat (luncheon meat, bacon, hot dogs, sausages) are more likely to get colon cancer than those who eat these foods only once in a while.

If red meat is eaten at all, limit your intake to less than three ounces (90 grams) a day. Choose fish, chicken, turkey, legumes, tofu and soy foods more often.

Cut down on fatty foods

Studies suggest that the more animal (saturated) fat people eat, the more likely they are to get colon cancer. Fatty foods might induce the cancer by increasing the secretion of toxic bile acids into the colon and stimulating the production of insulin.

Limit your intake of ice cream, cheese, rich desserts and deep-fried foods. Choose nonfat dairy products and use high-fat spreads like butter and cream cheese sparingly, if at all.

Cut down on alcohol

In a study of more than 45,000 male health professionals, drinking more than two alcoholic drinks a day doubled the risk of colon cancer. Based on these and other similar findings, cancer experts advise drinkers to limit alcohol intake to seven drinks a week for women and nine for men.

Alcohol may stimulate the growth of colon cancer cells, activate cancer-causing substances and help transform polyps into cancer. Alcohol also interferes with the body's use of folate, a B vitamin needed for the repair of DNA in cells. If you do drink, increase your intake of folate-rich foods such as spinach, lentils, asparagus, avocado and oranges.

Eat more whole grains

The relationship between a high-fibre diet and colon cancer risk remains unclear, but evidence suggests that eating more whole grains can lower the risk. Whole grains such as barley, brown rice, oats, whole wheat, whole rye and quinoa contain a "package" of nutrients and phytochemicals that are thought to work together to guard against cancer. At least half your daily grain servings should be whole grain.

Leslie Beck