Physical activity may lower breast cancer risk

NEW YORK (Reuters Health) - A new study in the journal Epidemiology adds to evidence that women can cut their breast cancer risk by being physically active.

Dr. Beata Peplonska of the Nofer Institute of Occupational Medicine in Lodz, Poland, and her colleagues also found that the benefits appeared to be particularly strong for women who boosted their recreational activity levels in their 50s.

There is a growing body of research showing that very active women are significantly less likely to develop breast cancer than their sedentary peers, Peplonska and her team note, but there is less information on whether the timing of exercise during a woman's life also influences the risk, and whether moderate physical activity is also beneficial.

To investigate, the researchers compared 2,176 women with breast cancer and 2,346 healthy controls. All were asked about their level of recreational and occupational physical activity throughout their adult lives.

The women with the highest total adult lifetime activity were 20 percent less likely to have developed breast cancer than the least active women, the researchers report in the medical journal Epidemiology.

Being in the top fourth of the group based on moderate-to-vigorous recreational physical activity conferred a 26 percent lower risk of the disease compared to being in the bottom fourth.

Furthermore, exercise was beneficial no matter whether a woman was slim, normal weight, or overweight; whether or not she had a family history of breast cancer; and whether or not she had reached menopause.

In fact, women who spent more time in moderate-to-vigorous recreational activities in their 50s than they had in their 20s, 30s and 40s were 34 percent less likely to develop breast cancer, while those who increased their activity the most were at 41 percent lower risk, Peplonska's team found.

They conclude: "Although the beneficial role of engaging in physical activity was observed for all age periods, our study suggests that increases in activity levels when a woman is in her 50s might be particularly relevant."

SOURCE: Epidemiology, March 2008.