Endocrine effects of letrozole + triptoreline compared to tamoxifen + triptoreline as adjuvant treatment of premenopausal patients with early breast cancer

Abstract

578 Background: Few data have been reported on endocrine effects of combining LHRH-analogues with aromatase inhibitors (AI) in premenopausal patients. However, promising data in postmenopausal patients make this information interesting in view of extending adjuvant AI to premenopausal patients. We are conducting a phase 3 trial (Hormonal adjuvant treatment bone effects (HOBOE)) comparing tamoxifen (Tam), letrozole (L) and L + zoledronate (Z) for the effect on bone mineral density at 1 year. Postmenopausal and premenopausal patients are eligible, the latter also receiving monthly triptorelin (Tr). Methods: This analysis is limited to 76 premenopausal patients with early endocrine-responsive breast cancer, 28 treated with Tam+Tr and 48 with L+Tr±Z, assuming that Z has no endocrine effects. Serum 17-β-estradiol, FSH, LH, Δ4-androstenedione, testosterone, dehydroepiandrosterone-solphate, progesterone, ACTH and cortisol are measured at baseline and after 6 months of treatment. We compared, for each hormone, 6-month values between treatment groups by applying Exact Wilcoxon-Mann-Whitney test. Results: Baseline values for all the hormones were comparable between treatment groups. At 6 months, statistically significant differences were found for estradiol, FSH, LH and cortisol (see table , with median and range values by treatment group). No differences were found in plasma levels of testosterone, progesterone, ACTH, androstenedione, and dehydroepiandrosterone between the two groups. Conclusions: These data support that letrozole compared to tamoxifen, in combination with triptorelin, induces a more intense estrogen suppression also in premenopausal patients. Such evidence makes reasonable the hypothesis that the higher efficacy of letrozole versus tamoxifen shown in postmenopausal patients could be confirmed also in premenopausal patients. [Table: see text] No significant financial relationships to disclose.