Prospective Study on the Effect of Toremifene in Patients With Adjuvant Anastrozole Failure in Postmenopausal Breast Cancer

Abstract

Purpose; An endocrine treatment using aromatase inhibitor (AI) is a standard strategy for postmenopausal patients with hormone receptor positive breast cancer. Postmenopausal patients who relapsed during adjuvant AI treatment or progression within a year after completion of AI treatment were prospectively treated with 40 mg/day of toremifene (TOR) in order to examine the effect of the selective estrogen receptor modulator (SERM) in AI-refractory patients. Patients and Methods; Twenty-three postmenopausal breast cancer patients who relapsed during adjuvant AI treatment or relapsed within a year after completion of AI were enrolled in the prospective trial from January 2007 to February 2010. Out of the patients, 14 cases had measurable or evaluable lesions, and the other had only bone metastasis. All patients were treated with toremifene of 40 mg/day. The primary efficacy end point for the trial was clinical response and secondary end point was progression free survival (PFS). Result; The objective response rate in the patients with measurable lesions was 7.1% (1/14) and clinical benefit rate was 28.6%. In the patients with evaluable bone disease, clinical benefit was 44.4%. No serious adverse event was observed except a patient with grade 3 non-hematological toxicity (AST and ALT). Conclusion; The SERM, toremifene (40 mg/day), demonstrated a safe profile and a favorable effect on disease control after adjuvant AI failure.