A study published by the American Cancer Society has found that postmenopausal women who lose weight have a reduced risk of developing invasive breast cancer compared to those who maintain or gain weight.
A strong link has been well-established between obesity and breast cancer risk, but studies on a possible link between lower breast cancer risk and weight loss in postmenopausal women have had mixed results.
To investigate, Dr. Rowan Chlebowski of the City of Hope National Medical Center and his team analyzed data on 61,335 women participating in the World Health Initiative Observational Study.
The participants had no history of breast cancer or abnormal mammogram results. At the beginning of the study, the women’s body weight, height, and body mass index were measured, and these measurements were followed up on every three years.
During an average follow-up of 11.4 years, 3,061 new cases of invasive breast cancer were diagnosed. Women with weight loss had a 12 percent lower breast cancer risk compared to women with stable weight. Overall, weight gain was not associated with a higher risk of invasive breast cancer, but was associated with a 54 percent higher incidence of triple negative breast cancer.
“Our study indicates that moderate, relatively short-term weight reduction was associated with a statistically significant reduction in breast cancer risk for postmenopausal women,” said Dr. Chlebowski.
“These are observational results, but they are also supported by randomized clinical trial evidence from the Women’s Health Initiative Dietary Modification trial where, in a randomized clinical trial setting, adopting a low-fat dietary pattern that was associated with a similar magnitude of weight loss resulted in a significant improvement in breast cancer overall survival.”
“These findings, taken together, provide strong correlative evidence that a modest weight loss program can impact breast cancer.”
The study is published in the journal CANCER.