Changes in Thyroid Functional Tests in Breast Cancer Patients under Tamoxifen Therapy

Tamoxifen, a synthetic anti-estrogen agent, is administered as anadjuvant treatment in breast cancer. since various studies have indicated thattamoxifen can change some hormones and bound globolines, controversial resultshave been achieved using this medicine on thyroid functional tests (tft). the presentstudy was conducted to investigate the effects of tamoxifen on tft in women withbreast cancer referred to oncology clinic in imam hossein hospital between 2001and 2002.method: a quasi-experimental clinical trial study was performed on 23 women withbreast cancer in a single blind basis (with no control group). patients were undertamoxifen 20 mg p.o. daily and their serum tsh, free t4 and three iodothyronine(t3) were assessed before treatment with tamoxifen and after 3 months. paired ttest was used for statistical analysis.results: there was a significant difference in t3 before and after the treatment withtamoxifen (p=0.02), whereas no significant differences were seen in tsh (p=0.095)and ft4 (p=0.13).discussion: this study showed that treatment with tamoxifen in women sufferingfrom breast cancer results in an increase in serum t3 but has no effect on serum tshand ft4, therefore women under treatment with tamoxifen remain euthyroid.