Early-Life Factors and Breast Cancer Risk in Hispanic Women: the Role of Adolescent Body Size

Background: Adult body size has long been known to influence breast cancer risk, and there is now increasing evidence that childhood and adolescent body size may also play a role. Methods: We assessed the association with body size at ages 10, 15, and 20 years in 475 premenopausal and 775 postmenopausal Hispanic women who participated in a population-based case-control study of breast cancer conducted from 1995 to 2004 in the San Francisco Bay Area. We used unconditional logistic regression to estimate ORs and 95% CIs for the associations with self-reported relative weight compared with peers and body build at ages 10, 15, and 20 years. Results: In premenopausal women, we found inverse associations with relative weight compared with peers, with ORs of 0.63 (P-trend = 0.05), 0.31 (P-trend < 0.01), and 0.44 (P-trend = 0.02) for heavier versus lighter weight at ages 10, 15, and 20 years, respectively. These inverse associations were stronger in currently overweight women and U.S.-born women and did not differ significantly for case groups defined by estrogen receptor status. In postmenopausal women, not currently using hormone therapy, inverse associations with relative weight were limited to U. S.-born Hispanics. Conclusions: Large body size at a young age may have a long-lasting influence on breast cancer risk in premenopausal, and possibly postmenopausal, Hispanic women that is independent of current body mass index. Impact: These findings need to be weighed against adverse health effects associated with early-life obesity. Cancer Epidemiol Biomarkers Prev; 20(12); 2572-82. (C) 2011 AACR.