Selenium levels in nails of premenopausal breast cancer patients assessed prediagnostically in a cohort-nested case-referent study among women screened in the DOM project.

To determine the possible role of selenium in the pathogenesis of breast cancer, prediagnostic Se 77 m isotope levels in toenail clippings in premenopausal women were measured. The study was designed as a case-referent study nested in a cohort. Participants were recruited from the DOM-project breast-cancer screening cohorts. No decreased selenium levels were found up to two years prior to diagnosis, nor were Se levels different between prevalent and/or incident breast cancer cases, referents and women with benign breast disease. Se levels measured in nails could not detect women at higher risk for breast cancer. This study does not support the idea that Se supplementation could have a preventive potential for premenopausal breast cancer in women in the Netherlands.