Female Reproductive Hormones and Biomarkers of Oxidative Stress in Postmenopausal Women With Breast Cancer

Abstract only Background: Female reproductive hormones have been implicated in the etiology of breast cancer, while oxidative stress induced by reactive oxygen species have been linked to various steps involved in carcinogenesis including cellular transformation, proliferation and metastasis. Aim: This study assessed the serum levels of estradiol (E 2 ), prolactin (PRL) and some biomarkers of oxidative stress in relation with clinical staging in postmenopausal women with breast cancer. Methods: One hundred postmenopausal women aged 50 to 70 years comprising of 50 women with breast cancer (with clinical staging II-IV) and 50 healthy women without breast lump or cancer were recruited into this case control study. Estradiol and prolactin were determined by enzyme linked immunosorbent assay, total antioxidant capacity (TAC), total plasma peroxides (TPP), malondialdehyde (MDA), glutathione (GSH) and nitric oxide (NO) were estimated by colorimetric methods while oxidative stress index was determined by calculation. Sociodemographic data and anthropometric indices (body mass index (BMI)) were obtained by standard methods. Data were analyzed using Student t-test, ANOVA and Pearson's correlation at P < 0.05. Results: The percentage of women with breast lump, breast pain, nipple discharge, high alcohol and fat intake were higher in women with breast cancer compared with women without breast cancer ( P < 0.05). The mean age at menarche, TAC, TPP, OSI, NO and E 2 levels were significantly lower and BMI higher in controls compared with breast cancer subjects ( P < 0.05). Women without breast cancer had lower TPP, OSI and E 2 compared with stage II; lower TAC, TPP, NO and E 2 compared with stage II; and lower MDA, NO and E 2 compared with stage 4 respectively ( P < 0.05). Positive correlations were observed between PRL and TAC (r=0.336, P = 0.011); PRL and E 2 (r=0.296, P = 0.037) and negative correlation between NO and E 2 (r=-0.295, P = 0.038), NO and MDA (r=-0.302, P = 0.033) only in women with breast cancer. Conclusion: Breast cancer is associated with increased lipid peroxidation, nitric oxide and oxidative stress index which may be involved in the progression of the disease.