Phase II clinical trial of high-dose toremifene as primary hormone therapy in aromatase inhibitor-resistant breast cancer.

Third-generation aromatase inhibitors(AIs)are now common in adjuvant hormone therapy for breast cancer in postmenopausal women. However, a suitable treatment has yet to be established for patients who develop cancer recurrence during or after adjuvant AI therapy. This prospective study evaluated the efficacy and safety of 120mg/day toremifene citrate(TOR-120)administered orally to 23 patients with recurrent breast cancer who were receiving or had received adjuvant AI therapy. Primary therapy for recurrence was TOR-120 monotherapy. The response rate was 13. 0%(partial response: three patients), the clinical benefit rate was 78. 3%(partial response: three patients; long-term stable disease: 15 patients), and median time to progression was 8. 1 months. Grade 1 adverse events such as loss of appetite, sweating, flushing and edema face were observed. TOR-120 monotherapy was effective and safe as a primary hormone therapy for recurrent breast cancer unresponsive to AIs.