Study finds weight gain after age 50 associated with increased risk for postmenopausal breast cancer
| August 03, 2005 | |
| CHAPEL HILL — Weight gain of more than 24 pounds in women older than 50 years of age – regardless of baseline weight at age 50 – is associated with a 62 percent increased risk for postmenopausal breast cancer compared with women with stable weight, a new study has found.The research team, led by a University of North Carolina at Chapel Hill epidemiologist, also found that women who had gained more than 33 pounds since age 20 were at a 60 percent increased risk of the disease compared with those with unchanged weight.
The study, published in today’s (Aug. 1) issue of the American Journal of Epidemiology, included women with breast cancer and those without the disease or “controls.” The investigators found that among women with tumors that were estrogen receptor positive and progesterone receptor positive, the increase in breast cancer in relation to weight gain was more pronounced. Hormone receptor positive breast cancer is the type of breast cancer that is most frequently diagnosed among American women. Furthermore, the scientists also found that among women who do not use hormone replacement therapy, those who gain weight after age 50 have twice the risk of the disease than those who maintain a stable weight after age 50. Among those who had used hormone replacement therapy, weight gain since age 50 had little or no effect on breast cancer risk. These results indicate that the impact of weight gain is only apparent among women who are not already exposed to other high sources of estrogen, said Dr. Marilie Gammon, professor of epidemiology at UNC’s School of Public Health. Estrogen is a steroid hormone that increases a woman’s risk of breast cancer. Fat tissue has enzymes that convert compounds in the body to estrogen. Thus, among overweight and obese postmenopausal women, fat tissue is an important source of estrogen. The results came from an analysis of the data collected on women who participated in the Long Island Breast Cancer Study Project, a multidisciplinary, multi-institutional collaboration to identify environmental risk factors for the disease. Dr. Sybil Eng, now at Pfizer Pharmaceuticals and formerly of Columbia University, is first author of the article. The Long Island Breast Cancer Study Project was funded by the National Cancer Institute and the National Institute of Environmental Health Sciences and includes more than 3,000 residents of New York’s Nassau and Suffolk counties. Gammon is the Long Island study’s principal investigator, a member of the UNC Lineberger Comprehensive Cancer Center and deputy director of UNC’s Center for Environmental Health and Susceptibility. “Our research question was, ‘How do body size changes, particularly later in life, affect breast cancer risk?'” she said. “Our analysis also showed that weight loss over a woman’s lifetime was associated with decreased risk of postmenopausal breast cancer.” The study found that women who lost weight since early adulthood – defined as age 20 – had a 45 percent decreased risk of postmenopausal breast cancer compared with women whose size remained the same during this time period. Gammon said “our data are consistent with the few other studies that have examined weight gain in later adulthood and weight loss in early adulthood. These data underscore efforts urging women to avoid weight gain as they age.” In addition to Eng and Gammon, the other scientists were Drs. Mary Beth Terry and Alfred Neugut of Columbia University, Dr. Lawrence Kushi of Kaiser Permanente and Drs. Susan Teitelbaum and Julie Britton of Mount Sinai School of Medicine. – 30 – Note: Contact Gammon at (919) 966-7421. Contact Eng at (212) 733-3316. UNC Lineberger contact: Dianne Shaw, (919) 966-5905 or dgs@med.unc.edu News Services contact: Deb Saine, (919) 962-8415 or deborah_saine@unc.edu For further information please contact Ramona DuBose by email at ramona_dubose@unc.edu |
