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

The former fought colon cancer recurrence, the latter lowered insulin levels in breast cancer survivors

SUNDAY, June 3, 2007 (HealthDay News) -- In an era of highly complex medications with highly complex mechanisms and even more complicated names, take comfort that some basic (and pronounceable) lifestyle changes can have an impact on cancer outcomes.

Diet and exercise still matter, according to two studies that were presented Saturday at the American Society of Clinical Oncology annual meeting in Chicago.

One study found that individuals with stage III colon cancer who had undergone surgery and chemotherapy had higher odds of relapsing or dying if they followed a predominantly "Western" diet of red meat, fat, refined grains and dessert.

"This is the first large amount of data to look at whether diet affects colon cancer survivors, and the suggestion is that dietary factors may have an effect," said study author Dr. Jeffrey Meyerhardt, an assistant professor of medicine at Dana-Farber Cancer Institute and Harvard Medical School, both in Boston. "Certainly we need more studies to understand the patterns. We also need to emphasize that diet is not a substitute for standard treatment."

Dr. Neal Meropol, director of the Gastrointestinal Cancer Program at Fox Chase Cancer Center in Philadelphia, added: "This suggests that diet can influence not only the development of cancer, but the chance that your colon cancer will come back. This is a very important result because it suggests that one can make a behavioral adjustment that could reduce their risk of dying from colon cancer."

Meropol emphasized, however, that the issue of diet and cancer development or recurrence is an extremely complex one.

People with stage III colon cancers have positive lymph nodes, although the cancer does not indicate any evidence of spreading outside of the local colon area. Standard treatment is surgery followed by chemotherapy.

More than 1,000 patients with stage III colon cancer who were participating in a trial of adjuvant chemotherapy were asked to complete questionnaires on their diet for six months after the chemotherapy ended. Researchers then tracked the participants to see if their cancer recurred or if they died.

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.

SOURCES: Jeffrey Meyerhardt, M.D., assistant professor, medicine, Dana-Farber Cancer Institute and Harvard Medical School, Boston; Jennifer Ligibel, M.D., instructor, medicine, Dana-Farber Cancer Institute and Harvard Medical School, Boston; Neal Meropol, M.D., director, Gastrointestinal Cancer Program, Fox Chase Cancer Center, Philadelphia; June 2, 2007, presentations, American Society of Clinical Oncology annual meeting, Chicago
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