SAN FRANCISCO -- April 9, 2002 -- Gaining more than 50 pounds during pregnancy, and not losing the excess weight post-pregnancy, could triple a woman’s risk of developing breast cancer after menopause, according to a large Finnish study.
The researchers at Lombardi Cancer Center in Washington, DC, and in Finland based their findings on data collected from more than 27,000 breast cancer patients in Finland, identified through a national cancer registry.
Study co-author Dr. Leena Hilakivi-Clarke, associate professor of oncology at the Lombardi Cancer Center at Georgetown University Medical Center says the study showed that pregnancy weight gain of 40 pounds increased breast cancer risk by 40 percent. The findings were presented today at the American Association for Cancer Research (AACR) annual meeting in San Francisco.
“Significant weight gain during pregnancy may cause changes in breast tissue that increase susceptibility to breast cancer in later life—roughly equivalent to the risk of postmenopausal obesity,” said Hilakivi-Clarke in a prepared statement. “Women who retain the added pounds after pregnancy are at the greatest risk.”
The study showed that weight gain during pregnancy appeared to increase breast cancer risk only after menopause, Hilakivi-Clarke said, adding that each 1 kg (2.2 pounds) increase in pregnancy weight increased breast cancer risk by 3.9%, when adjusted for body mass index before pregnancy.
Weight gain of 25 to 35 pounds is normal in pregnancy and was not associated with an increased risk for either premenopausal or postmenopausal breast cancer, Hilakivi-Clarke said.
Pregnancy weight gain has been linked in previous studies to increased estrogen levels, which in turn are believed to increase breast cancer risk, researchers said. Information about breast cancer diagnosis and pregnancy weight gain were obtained from a national cancer registry, maternity center registries and from a questionnaire completed by the study participants.
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