According to the results of a study published in the journal Breast Cancer Research and Treatment, risk of breast cancer among women with a BRCA1 or BRCA2 mutation may be increased by high caloric intake or weight gain during adulthood.
Inherited mutations in two genes-BRCA1 and BRCA2-have been found to greatly increase the lifetime risk of developing breast and ovarian cancer. Alterations in these genes can be passed down through either the mother’s or the father’s side of the family.
Among women with a BRCA1 or BRCA2 mutation, an important goal of research is to identify treatments, screening tools, and behavioral changes that can reduce the risk of developing breast cancer or improve early detection of cancer.
Two recent studies among women without a BRCA1 or BRCA2 mutation suggested that weight gain during adulthood can greatly increase the risk of developing postmenopausal breast cancer.,  Less is known about the effects of diet, weight gain, and physical activity among women with a BRCA1 or BRCA2 mutation.
To evaluate dietary and lifestyle factors in relation to breast cancer risk among women with a BRCA1 or BRCA2 mutation, researchers conducted a study among 137 French-Canadian women. Eighty-nine of the women had developed breast cancer and 48 had not.
- After accounting for age, body mass index, and physical activity, women who reported higher caloric intake had an increased risk of breast cancer. Risk of breast cancer was almost three times higher among women who reported the highest levels of caloric intake than among women who reported the lowest levels of caloric intake.
- The intake of other nutrients did not appear to influence breast cancer risk.
- Women who had gained the most weight in adulthood (after the age of 18) had a more than four-fold increase in breast cancer risk. Weight gain after the age of 30 was also linked with an increased risk.
These results suggest that weight control in adulthood may be important in reducing the risk of breast cancer among women with a BRCA1 or BRCA2 mutation.
 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.