Toremifene as a substitute for adjuvant tamoxifen in breast cancer patients

Background: Toremifene is a new antiestrogen, which in nonclinical studies appears less carcinogenic than tamoxifen. Clinical trials of adjuvant torem ifene vs, tamoxifen in breast cancer patients ave ongoing. This study aimed to evaluate the short-term effects of changing from adjuvant tamoxifen to toremifene. Patients and Methods: Twenty postmenopausal breast cancer patie nts receiving adjuvant tamoxifen, 20 mg/day, were switched to toremifene 60 mg/day. The effects on the uterus were evaluated prospectively by transvag inal ultrasound; tolerability was assessed clinically. Results: In 14 patie nts who had uterine abnormalities (endometrial thickening or polyps) under tamoxifen, no significant changes occurred during a median of 18 months (ra nge 7-24) of toremifene treatment. Out of six patients who had entered the study due to intolerance to tamoxifen, however; 3 tolerated toremifene well . Conclusion: Toremifene does not modify previous uterine changes induced b y tamoxifen. For some patients who do not tolerate tamoxifen, however, swit ching to toremifene may allow the continuation of adjuvant antiestrogenic t herapy.