PURPOSE - We assessed the association between diabetes and breast cancer and whether physical activity modified the effect of diabetes on breast cancer in Hispanic women.
METHODS - We used data from a case-control study of breast cancer among Hispanic women aged 30-79 conducted between 2003 and 2008 on the Texas-Mexico border. In-person interviews were completed with 190 incident breast cancer cases ascertained through surgeons and oncologists, and 979 controls who were designated as both high-risk (n=511) and low-risk (N=468) for breast cancer (with respective response rates of 97%, 83% and 74%).
RESULTS - After adjustment for menopausal status and mammography screening, there was no effect of diabetes on breast cancer risk (high-risk control group odds ratio [OR] 1.02, 95% confidence interval [CI] 0.71-1.48; low-risk control group OR 0.87, 0.58-1.30). Women who had a diabetes history and did not exercise were at no risk of breast cancer (OR 0.96, 95% CI 0.63-1.48) or a slightly reduced breast cancer risk (low-risk control group OR 0.72, 95% CI 0.46-1.15) depending on the control group used, while women with diabetes who did exercise had significantly reduced breast cancer risk (OR 0.41, 95% CI 0.21-0.83) regardless of the control group used (high-risk control group p-value for interaction=0.013, low-risk control group p-value for interaction 0.183).
CONCLUSIONS - Should other studies confirm our results, physical activity should be explored as a means of reducing breast cancer risk in diabetic women.
Copyright © 2010 Elsevier Ltd. All rights reserved.