Heavier Young Women at Lower Breast Cancer Risk

But overweight is linked to other health woes, experts warn.

By Amanda Gardner
HealthDay Reporter
Tuesday, November 28, 2006; 12:00 AM

Copyright © 2006 ScoutNews, LLC. All rights reserved.

TUESDAY, Nov. 28 (HealthDay News) -- Women who are heavier in young adulthood have a lower risk of developing breast cancer before they reach menopause, new research shows.

The finding, published in the Nov. 27 issue of the Archives of Internal Medicine, confirms and expands on previous research suggesting that larger body size before menopause helps fend off breast cancer.

That's not a license for women to gain weight, however, experts stressed.

"We have to remind women that obesity is pretty much bad for everything else and, as soon as you become postmenopausal, obesity is one of the strongest predictors of breast cancer," said lead researcher Karin B. Michels, an associate professor of obstetrics, gynecology and reproductive biology at Harvard Medical School and Brigham and Women's Hospital in Boston.

"It's never a good idea to be obese because of other health effects," added Dr. Jay Brooks, chairman of hematology/oncology at Ochsner Health System in Baton Rouge, La. "The problem is that women who are postmenopausal, which is where the largest number of breast cancers are, have a very hard time losing weight."

Recent research has shown that postmenopausal women can cut their breast cancer risk by shedding extra pounds.

However, the situation is somewhat different for younger, premenopausal females. In this group, prior studies had shown that as body-mass index (BMI) went up, breast cancer risk declined.

Some had speculated that this was because a higher BMI is associated with irregular or long menstrual cycles and the development of polycystic ovary syndrome --- all of which are associated with problems in ovulation. Ovulatory dysfunction, in turn, decreases levels of estrogen and progesterone. Lower levels of these sex hormones -- long linked to breast cancer -- could account for a lowered risk of malignancy.

For this study, Michels and her colleagues tracked outcomes for more than 113,000 premenopausal women who were part of the Nurses' Health Study II, a group of female registered nurses who have been followed by researchers since 1989. The women were followed until 2003, or until they developed breast or other cancer, died or reached menopause, whichever came first.