Effects of exemestane and tamoxifen on hormone levels within the Tamoxifen Exemestane Adjuvant Multicentre (TEAM) trial: results of a German substudy.

Aim: The aim of this study was to compare the effects of exemestane and tamoxifen on hormone levels in postmenopausal patients with hormone receptor-positive breast cancer within a Germany substudy of the Tamoxifen Exemestane Adjuvant Multinational (TEAM) trial.
Methods: Within the TEAM trial, patients were randomized to receive adjuvant treatment with exemestane for 5 years or tamoxifen for 2.5-3 years followed by exemestane for 2-2.5 years. Serum levels of testosterone, dehydroepiandrosterone sulfate (DHEAS), sex hormone binding globulin (SHBG), follicle stimulating hormone (FSH) and parathyroid hormone (PTH)-intact were measured at screening and after 3, 6 and 12 months of treatment.
Results: Data on hormone levels were available from 63 patients in the tamoxifen arm and 68 patients in the exemestane arm. Treatment with exemestane resulted in decreases from baseline in SHBG and PTH-intact levels, and increases from baseline in testosterone, DHEAS and FSH levels. Tamoxifen treatment resulted in increases from baseline in SHBG and PTH-intact, whereas levels of testosterone and FSH decreased and DHEAS levels did not change. At all time points assessed, the absolute change from baseline was significantly different between tamoxifen and exemestane for testosterone, SHBG, FSH and PTH-intact (all p < 0.0001).
Conclusions: Exemestane and tamoxifen had statistically significantly different effects on hormone levels, including testosterone, SHBG, FSH and PTH-intact.