Healthy Diet, Exercise Might Lower Chances of Cancer's Return

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Dietary patterns fell into two categories: "Western," which involved a high intake of red meat, fat and dessert, and "prudent," meaning high fruit, vegetable, poultry and fish consumption.

The two dietary patterns did not necessarily preclude each other. "Everyone has some score for each of those patterns," Meyerhardt stated. "Someone might eat a lot of hamburger and a lot of vegetables."

People who consumed the highest levels of the Western diet had almost quadruple the risk of recurrence or death compared with those who consumed the least in this category.

"Those who had a higher intake of a Western-pattern diet characteristic of more red meat and dessert had a significantly higher risk of recurrence and mortality, about four times as high," Meyerhardt said.

What's interesting is that the dietary pattern seemed to have an effect in a relatively short period of time -- years, as opposed to a lifetime. Why? One hypothesis is that this type of diet stimulates some growth factors that allow the growth of microscopic disease, Meyerhardt said.

But it also raises the question of whether the study participants had modified their diet after their diagnosis or whether this was a continuation of past patterns. "Future research should be geared toward answering that very question, whether changing a diet from Western to prudent would in fact reduce the risk of dying from colon cancer," Meropol said.

A second study, also from Dana-Farber, found that previously sedentary breast cancer survivors who exercised reduced the amount of insulin in their blood. It was unclear, however, what effect this might have on cancer recurrence, but the suggestion is that insulin levels may explain why physical activity has been associated with better outcomes.

Previous studies have shown that women who shed extra pounds and became more physically active had a lower risk of breast cancer recurrence. Women who are obese at the time of diagnosis, by contrast, have a higher level of recurrence.

For this study, researchers assigned 101 women with breast cancer to a 16-week program of cardiovascular exercise and strength training or to "normal" care. All women had their insulin and blood glucose levels measured, as well as their weight, body composition, and waist and hip circumference. Participants had already completed chemotherapy and/or radiation but had not started on any hormonal therapies, said study author Dr. Jennifer Ligibel, an instructor of medicine at Dana-Farber and Harvard.

Women in the exercise group lowered their insulin levels by about 20 percent, Ligibel said, an amount that approached statistical significance. These women also had a trend toward improved insulin sensitivity, meaning how their body responds to the hormone insulin.

"The ultimate goal is to look at exercise vs. not exercising and see what happens to women's breast cancer," Ligibel said.

More information

Visit the American Cancer Society for more on diet, physical activity and cancer.