Premenopausal Breast Cancer Risk Lower with High BMI
Body mass index of 27.5 or greater at age 18 associated with lower risk
MONDAY, Nov. 27 (HealthDay News) -- A relatively large body mass index, or BMI, in young adulthood seems to protect against premenopausal breast cancer, according to a report published in the Nov. 27 issue of the Archives of Internal Medicine.
Karin B. Michels, Ph.D., of Harvard Medical School in Boston, and colleagues evaluated 1,398 cases of invasive breast cancer diagnosed between 1989 to 2003 in 113,130 premenopausal women. Height, weight, ovulation and menstrual cycle were among the variables analyzed.
The investigators found a linear inverse relationship between current BMI and breast cancer, with a hazard ratio of 0.81 for women with a BMI of 30 or more compared to women with a BMI between 20 and 22.4. The difference could not be attributed to menstrual cycle features or ovulatory disorders. A large body mass at 18 years was the strongest predictor for breast cancer. The adjusted hazard ratio was 0.57 for women with a BMI of 27.5 or greater at 18 years of age compared with women with a BMI between 20 and 22.4 at age 18.
"Large body size during early adulthood is inversely related to the incidence of breast cancer in premenopausal women. Factors related to ovulation, such as menstrual cycle characteristics, infertility due to an ovulatory disorder and probable polycystic ovary syndrome, do not seem to explain this association," the authors conclude.