Toenail selenium levels and the risk of breast cancer.

The association between toenail selenium and breast cancer was studied in a prospective study on diet and cancer among 62,573 Dutch women aged 55-69 years that started in September 1986. The analysis was based on 355 breast cancer cases, detected during 3.3 years of follow-up (1986-1989), for whom selenium data were available. Selenium levels were significantly lower among cases diagnosed early during follow-up. After exclusion of cases that occurred in the first year of follow-up, multivariable-adjusted rate ratios of breast cancer in increasing quintiles of selenium were 1.00, 0.90, 0.76, 0.86, and 0.91 (trend p = 0.618). The authors found no evidence for an inverse association between selenium status and breast cancer.