THE EFFECT OF LONG TERM TAMOXIFEN THERAPY ON THYROID FUNCTIONS IN BREAST CANCER

Thyroid function studies have been evaluated in 32 patients with cancer of the breast in different clinical stage and histology who had been on Tamoxifen 20 mg/day for a median of 9 months (Ranging 3-24 months). 9 per cent of the patients were premenapausal whereas 91 per cent were postmenapausal. Prerequisite for inclusion to the study was at least 6 months chemotherapy-free period prior to the study. All cases had been previously mastectomized. Terminal cases and the patients with established thyroid diseases were excluded from the evaluation. Total T4,T3 Resin Uptake Free Thyroxin Index and TSH were measured prior to Tamoxifen therapy as well as during the therapy in 3 months intervals. Of the total 32 patients, minimal TT4 elevations were dedected in 2 cases (13.15 ug/ml,N:4.5-121.5 ug/ml) T3RU and TT4 were found to below in one (%21,N:%25-37 and 2 ug/ml) and serum TSH were minimaly low in two (1.1 and 0.1 mIU/ml,N:0,2-4.0 mlU/ml). The patients with elevated levels of TT4 had been on Tamoxifen therapy for 9 months and 3 months respectively. Mean and ranges were dedected as follows: 8 ug/ml (R:2.0-15.0), T3RU:%25.5 (R:%21-36), TSH: 1.08 IU/ml (R:0.1-3.0), FTI: 2.27 (R: 1.7-3.6). There was no statistical difference between these findings and pre-therapy values.

Keywords: Breast cancer, tamoxifen therapy, thyroid functions