Women who gain weight after menopause increase their
risk of developing invasive breast cancer. Conversely,
weight loss reduces the risk, researchers report.
The findings come from an analysis of data from
the Nurses Health Study, published in the July 12
issue of the Journal of the
American Medical Association.
Dr. A. Heather Eliassen, from Brigham and Women's
Hospital in Boston, and her team point out that many
studies have established the relationship between
weight gain and increased breast cancer risk. However,
the few studies that evaluated the effect of weight
change after menopause have yielded conflicting results.
They therefore studied these relationships in a group
of 49,514 women between 30 and 55 years old who were
premenopausal in 1976, had no history of cancer, and
became postmenopausal or underwent removal of both
ovaries over the course of the study.
At follow-up in 2002, there were 2376 cases of invasive
breast cancer among postmenopausal subjects whose
weight had been documented.
Dr. Eliassen and her team accounted for other risk
factors for breast cancer and found that the risk
of developing breast cancer for women who gained 25
kilograms or more since age 18 was 45 percent higher
than for those whose weight remained stable. The risk
was increased by 18 percent for women who gained 10
kg or more after menopause.
Among women who lost at least 10 kg before menopause,
the risk dropped 16 percent, while women who lost
at least 10 kg after menopause decreased their risk
by 23 percent. For those who maintained their weight
loss after menopause, the risk dropped by 57 percent.
However, few women lose weight after menopause, the
researchers point out. Therefore, "women should avoid
weight gain throughout adult life rather than count
on losing weight after menopause," Eliassen's group
advises, to cut the risk of breast cancer.
SOURCE: Journal of the American Medical Association,
July 12, 2006.
