[Efficacy and Safety of the Selective Estrogen Receptor Down-Regulator "Fulvestrant" in Japanese Patients with Advanced, Recurrent, ER-Positive Postmenopausal Breast Cancer].

Fulvestrant is a novel endocrine therapy for breast cancer that exerts both anti-estrogenic and down-regulatory effects by binding to and degrading estrogen receptors (ERs). In the present study, the safety and effectiveness of 500 mg fulvestrant in 69 patients with advanced, recurrent, ER-positive postmenopausal breast cancer were investigated retrospectively. Outcomes were favorable for fulvestrant. The objective response rate was 24.6%, the clinical benefit rate was 49.2%, the median progression-free survival (PFS) was 203 days, and the median overall survival was 794 days. PFS tended to be longer in patients without a history of previous treatment or visceral metastasis. The main adverse events included injection site reactions and hot flushes; however, the majority of these events were mild to moderate. The present findings suggest that, among Japanese patients with advanced, recurrent, ER-positive postmenopausal breast cancer, 500 mg fulvestrant is effective and safe in those without metastasis and a minimal history of receipt of previous treatment regimens.