Efficacy of fulvestrant 500 mg in Japanese postmenopausal advanced/recurrent breast cancer patients and factors associated with prolonged time-to-treatment failure

Objective: We aimed to confirm the efficacy of fulvestrant in Japanese postmenopausal advanced/recurrent breast cancer (ABC) patients, and investigate factors contributing to time-to-treatment failure (TTF) prolongation.Research design and methods: This retrospective study included 194 ABC patients who received fulvestrant (500 mg) from January 2012 to December 2014.Main outcome measures: TTF (efficacy measure), overall survival (OS), factors prolonging TTF and adverse events were evaluated.Results: The median age was 65 (42 – 90) years. Overall, TTF was 5.48 months. In patients without prior chemotherapy (n = 59), OS was significantly longer (p = 0.0131) than in patients with prior chemotherapy (n = 135). There was no strong correlation between TTF with fulvestrant and other endocrine therapies, total duration of endocrine therapy and maximum duration of endocrine therapy. TTF was significantly longer in patients with less than two prior chemotherapy regimens (p = 0.0093), de novo metastatic disease (p = 0.0124) and without liver metastasis (p = 0.0024). We observed one case each of pulmonary infarction and psychiatric disorder.Conclusions: Fulvestrant is effective for ABC patients and may show greater efficacy in patients with few prior chemotherapy regimens, de novo metastatic disease and absence of liver metastasis. Prior endocrine therapy duration might not be a predictive factor for fulvestrant TTF in heavily treated ABC patients.研究目的：本研究旨在确认氟维司群（fulvestrant）在日本绝经后晚期/复发性乳腺癌（ABC）患者中的疗效，并探究可延长治疗失败时间（TTF）的相关影响因素。研究设计与方法：本回顾性研究纳入了2012年1月至2014年12月期间接受氟维司群（500mg）治疗的194例ABC患者。主要结局指标：评估了治疗失败时间（TTF，疗效指标）、总生存期（OS）、可延长TTF的影响因素以及不良事件。结果：患者中位年龄为65岁（范围42~90岁）。整体人群的TTF为5.48个月。在未接受过既往化疗的患者（n=59）中，其总生存期显著长于接受过既往化疗的患者（n=135，p=0.0131）。氟维司群治疗的TTF与其他内分泌治疗、内分泌治疗总时长及内分泌治疗最长持续时长之间未观察到强相关性。在既往化疗方案少于2种、初诊转移性疾病且无肝转移的患者中，TTF显著更长（分别为p=0.0093、p=0.0124、p=0.0024）。本研究中分别观察到1例肺梗死与精神障碍病例。结论：氟维司群对ABC患者具有疗效，在既往化疗方案较少、初诊转移性疾病且无肝转移的患者中可能展现出更优的疗效。对于经多线治疗的ABC患者而言，既往内分泌治疗时长或许并非氟维司群TTF的预测因素。