Study: Few Hours of Exercise May Help Prevent Early Breast Cancer

Women who exercise even a few hours a week may reduce by a third their risk of developing breast carcinoma in situ, a condition that sometimes develops into invasive breast cancer, according to University of Southern California researchers.

Reporting in the journal Cancer, the researchers said that women who exercised appeared to have a 35 percent lower risk of developing breast carcinoma in situ than did inactive women.

Breast carcinoma in situ, or BCIS, consists of clusters of abnormal cells confined either to breast ducts or lobules. Most BCIS cases are found through screening mammograms. Left untreated, BCIS may develop into invasive breast cancer.

In a study that compared the exercise habits of 567 women diagnosed with BCIS with that of 616 disease-free women between the ages of 35 and 64, researchers found that the risk of BCIS was about 35 percent lower in those who exercised compared to those who were inactive.

Among women with no family history of breast cancer, the risk was reduced with increased exercise. Women who exercised more than four hours a week had a 47 percent lower risk of BCIS than inactive women. Physical activity did not reduce BCIS risk among women with a family history of breast cancer.

"Although we presume that physical activity works through a hormonal means to reduce BCIS risk, this may not be an important mechanism for women who may have a hereditary form of the disease," said Dr. Leslie Bernstein.

Other Sources: Cancer