Tissue antioxidants and postmenopausal breast cancer: the European Community Multicentre Study on Antioxidants, Myocardial Infarction, and Cancer of the Breast (EURAMIC)

Abstract

Antioxidants may protect against free radical mediated carcinogenesis. Epidemiological studies have not confirmed this hypothesis for breast cancer, possibly because of methodological limitations. Time-integrated exposure of alpha-tocopherol and beta-carotene in adipose tissue, and selenium in toenails was investigated in a case-control study among postmenopausal women, ages 50-74 years, from five European countries. The study group comprised 347 incident breast cancer cases and 374 controls. Mean antioxidant levels, adjusted for age and center, did not significantly differ for alpha-tocopherol (cases were 4.5% higher than controls), beta-carotene (3.0% lower), or selenium (1.8% lower). Odds ratios for highest versus lowest tertiles of exposure, adjusted for potential confounders, were 1.15 (95% confidence interval, 0.75-1.77), 0.74 (0.45-1.23), and 0.96 (0.63-1.47), respectively, without evidence for a decreasing trend. No statistically significant interactions were observed. Moreover, a provisional antioxidant score, indicating whether concentrations were above the median for zero, one, two, or all three antioxidants, yielded odds ratios of 1.00 (reference; all below median), 1.58, 1.58, and 1.21, respectively (chi2 for association = 4.00; P = 0.26). These results do not support the hypothesis that antioxidants are important determinants of this hormone-related malignancy among postmenopausal women.