The study reveals that the greater the weight gain as an adult, the greater the risk for all histological types, tumour stages, and grades of breast cancer, particularly advanced malignancies. The most extremely obese women were up to three times more likely to have regional or distant metastases than women with less weight gain. The study is the first to investigate the relationship between weight gain and type of breast cancer.
Previous studies have shown, that postmenopausal women who take hormone replacement therapy actually mitigate the effects of obesity on cancer risk. Moreover, current weight as defined by body mass index is not as important as a woman's weight gain from the age of 18. Led by Heather Spencer Feigelson, Ph.D., researchers investigated the risk between weight gain and type of invasive breast cancer among 44,161 postmenopausal women who were not taking hormone therapy.
The researchers found that the greater the weight gain, the greater the risk for all types, stages, and grades of breast cancer. Compared to women who gained 20 pounds or less during adulthood, women who gained over 60 pounds were almost twice as likely to have ductal type tumours and 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. As expected, weight gain increased the risk of estrogen receptor positive tumours, but not of tumours that did not present estrogen receptors.
Feigelson and her colleagues conclude that "these data further illustrate the relationship between adult weight gain and breast cancer, and the importance of maintaining a healthy body weight through-out adulthood."
MEDICA.de; Source: John Wiley & Sons, Inc.