Obesity may increase the risk of death from early-stage breast cancer, according to a new study from the University of Oxford.
The study focuses on estrogen receptor-positive, or ER-positive, breast cancer. Obese women who had not yet gone through menopause and had ER-positive breast cancer were more likely than other women to die of the disease, according to the study, an analysis of the results of 70 clinical trials.
These women were 34 percent more likely to die of their breast cancer. Obesity did not seem to have significant effect on death risk among postmenopausal women with ER-positive breast cancer or among those with ER-negative disease. According to the American Cancer Society, nearly two-thirds of breast cancers are hormone-receptor positive.
“This study forces us to pay attention to obesity in premenopausal women,” said Courtney Vito, M.D., a breast surgeon and assistant clinical professor of surgical oncology at City of Hope, in a HealthDay article.
The good news, she pointed out, is that unlike other risk factors, patients can take control of their weight.
“Once you are 50 and have breast cancer, you can’t go back and breast-feed, which reduces risk,” said Vito, who was not involved in the study. Women cannot change their family history or other risk factors. “But being overweight is something you can take control of.”
The study will be presented at the upcoming American Society of Clinical Oncology annual meeting in Chicago.
Previous research had indicated that obesity is a greater risk factor for developing breast cancer after menopause. This study evaluated the risk of breast cancer death in more than 80,000 women with early-stage breast cancer. The death rate was 34 percent higher among obese women who had ER-positive disease and had not yet gone through menopause compared to those of normal weight.
The researchers told HealthDay the findings seem counter-intuitive because obesity only significantly raises the level of estrogen in the blood after menopause. The researchers also considered tumor characteristics, type of treatment and other factors, but the link still held – but is not explained. While there is clearly an association between obesity and increase risk of death, there is not a cause-and-effect link that’s apparent.
Learn more about breast cancer research and treatment at City of Hope.
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