Women who gain weight in adulthood face a higher lifetime risk of all types of breast cancer, according to a study to be published in July in the journal CANCER from the American Cancer Society.
The risk is true even if the women do not take hormone replacement therapy after menopause. The researchers found that the greater the weight gain, the greater the risk for all types, stages, and grades of breast cancer.
Specifically, the researchers concluded that the greater the weight gain as an adult, the greater the risk for all forms of breast cancer. The most extremely obese women were up to three times more likely to have regional or distant metastases than women with less weight gain. For example, women who gained 20 pounds or less during adulthood were compared to women who gained over 60 pounds. The latter group have nearly two times the likelihood of developing ductal type tumors and are more than 1.5 times more likely to have lobular type cancers. The risk for metastatic disease increased for all women who gained weight, with the risk greater than three-fold for women who gained over 60 pounds. Also, weight gain increased the risk of estrogen receptor positive tumors, but not of tumors that did not present estrogen receptors, a release of the study findings states.