Evaluating Association of Tissue Selenium Level and Estrogen Receptor and Progesterone Receptor Expression in Breast Cancer

ABSTRACT Background and Objectives: Recently, the incidence of breast cancer has increased drastically worldwide. Therefore, the identification of novel diagnostic biomarkers is essential for improving treatment outcomes and prognosis. Estrogen receptor (ER) and progesterone receptor (PR) are routinely available in breast cancer specimens. Semi-quantitative assessment of ER and PR is important for prognosis. Even with the development of genomic tests, hormone receptor status remains the most significant predictive and prognostic biomarker. Selenium is known to protect mammary epithelial cells against oxidative DNA damage and early carcinogenetic events. Since overexpression of ER and PR is common in breast cancers, we aimed to evaluate association of tissue selenium level and ER and PR expression in breast cancer. Methods: Sixty tissue samples (30 tumors and 30 tumor margins) were collected from patients with breast cancer. Selenium level was measured using graphite furnace atomic absorption spectroscopy and ER/PR expression was evaluated using immunohistochemistry. Results: About 60% of the samples were positive for ER/PR expression. Mean level of tissue selenium was 209.54 µg/L in tumors and 185.04 µg/L in tumor margins that were ER/PR positive. In addition, mean selenium level was 243.39 µg/L and 168.06 µg/L in ER/PR-negative tumors and tumor margins, respectively. There was no significant association between selenium level and ER/PR expression (P>0.05). Conclusion: There is no association between tissue Se level and ER/PR expression in breast cancer. Keywords: Selenium, Estrogen receptor (ER), progesterone receptor (PR), breast cancer.