According to a study published in the journal Cancer, postmenopausal women who reported the most weight gain in adulthood had the highest risk of breast cancer; this increased risk was observed for most types and all stages of breast cancer.
To further understand the causes of breast cancer and possible approaches to breast cancer prevention, researchers have explored a variety of factors that may increase or decrease the risk of developing breast cancer. These factors include diet, physical activity, reproductive factors, and hormone use. Excess body weight is known to increase the risk of breast cancer among postmenopausal women, but there is less information about whether excess weight is linked with particular types or stages of breast cancer.
To evaluate the link between adult weight gain and type and stage of breast cancer, researchers evaluated information from the American Cancer Society’s Cancer Prevention II Nutrition Cohort. The study involved 44,161 postmenopausal women, 1,200 of whom developed breast cancer. The study included only women who were not using postmenopausal hormones.
- Women with the most weight gain in adulthood had increased risks of both ductal and lobular breast cancer. Compared to women who gained 20 or fewer pounds, women who gained more than 60 pounds were almost twice as likely to develop ductal carcinoma and roughly 50% more likely to develop lobular carcinoma.
- Weight gain increased the risk of breast cancer of all stages and grades, but seemed to have the greatest impact on regional and distant disease. Compared to women with the least weight gain, women with the greatest weight gain were more than three times more likely to develop regional or distant breast cancer.
- Weight gain increased the risk of estrogen receptor-positive/progesterone receptor-positive breast tumors, but not estrogen receptor-negative/progesterone receptor-negative breast tumors.
The researchers conclude that excess weight increases the risk of breast cancer among postmenopausal women, particularly the risk of advanced stage and high-grade breast cancer. The researchers note “Adult weight gain is one of the few well established risk factors for breast cancer that is modifiable. These data further illustrate the relation between adult weight gain and breast cancer and the importance of maintaining a healthy body weight throughout adulthood.”
Reference: Feigelson HS, Patel AV, Teras LR, Gansler T, Thun MJ, Calle EE. Adult Weight Gain and Histopathologic Characteristics of Breast Cancer Among Postmenopausal Women. Cancer. Early Online Publication May 22, 2006.
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