Serum selenium measurements in women with early-stage breast cancer with and without chemotherapy-induced ovarian failure

Blood selenium has been shown to decline as breast cancer progresses and fluctuate with estrogen. The objective of this study was to determine the effect of estrogen depletion resulting from chemotherapy-induced ovarian failure on serum selenium and selenoproteins in stage I/II premenopausal breast cancer patients. Serum selenium, glutathione peroxidase (GPx) activity, and selenoprotein P (SelP) were measured and a dietary questionnaire was completed at baseline (before chemotherapy) and 6, 12, and 24 months after start of chemotherapy. Twelve months after the start of adjuvant chemotherapy 33 (75%) patients developed ovarian failure (OF) and 11 (25%) retained menstrual function (non-OF). Dietary selenium intake was 30–58% above the Recommended Dietary Allowance for both groups. By six months the mean estradiol (pg/ml) was lower in the OF group than in the non-OF group (32±5 versus 140±62 pg/ml, p=0.01) and this difference was maintained at 12 and 24 months. However, there was no differences in serum selenium, GPx activity, or SelP in the OF and non-OF groups at 6, 12, and 24 months. Selenium status in premenopausal breast cancer patients, as measured by serum selenium, GPx and SelP, was within the normal range before and following adjuvant chemotherapy, and was not affected by chemotherapy-induced ovarian failure.