Weight Loss & Diet Plans

Weight Gain May Increase Breast Cancer Risk

Feb. 26, 2004 -- Women who put on more than 70 pounds as adults may be twice as likely to develop breast cancer during menopause as women who maintain their weight.

A new study suggests that for women not taking hormone replacement therapy (HRT), weight gain after age 18 may be a strong predictor of menopausal breast cancer risk.

Researchers found that postmenopausal women not taking HRT who gained more than 20 pounds since age 18 were much more likely to develop breast cancer than women who stayed within five pounds of their teenage weight.

"These findings further illustrate the importance of maintaining a healthy body weight throughout life," says researcher Heather Spencer Feigelson, PhD, MPH, senior epidemiologist at the American Cancer Society, in a news release. "Even modest weight gain since age 18 was associated with increased risk of postmenopausal breast cancer.

"Avoiding weight gain is one of the few ways we know of to reduce the risk of breast cancer among postmenopausal women," says Feigelson.

The findings appear in the February issue of Cancer Epidemiology, Biomarkers & Prevention.

Extra Pounds Increase Breast Cancer Risks

The study involved more than 62,000 postmenopausal women who took part in the American Cancer Society's Cancer Prevention Study II.

The women, who were between the ages of 50 and 74 at the start of the study in 1992, were asked about their current weight and their weight at age 18. Total weight change from age 18 to their age in 1992 was calculated. During the follow-up period, 1,934 breast cancer cases occurred among the participants.

Researchers found that among non-HRT users, women who gained 21 to 30 pounds since age 18 were 40% more likely to get breast cancer than women who had gained no more than five pounds. And the risks increased as the women's weights increased.

Women who gained more than 70 pounds were twice as likely to develop breast cancer as the women who maintained their weight.

Although adult weight gain was strongly related to breast cancer risk among non-HRT users, adult weight gain was unrelated to breast cancer risk among women on HRT. Breast cancer risks among these HRT users were nonetheless higher, regardless of adult weight gain.

Researchers say the findings support the idea that body fat increases menopausal breast cancer risk by increasing estrogen levels in the body. Women on HRT already have higher levels of estrogen as a result of the hormones they're taking, which may mask any additional effect of body fat.