Abstract P6-10-05: First-line chemotherapy versus first-line endocrine therapy in hormone receptor positive HER2 negative patients with metastatic breast cancer in China: Results of the study of breast cancer group of the Chinese Society of Clinical Oncology (CSCO)

Abstract

Background: The primary objective for metastatic breast cancer is to prolong the patients survival. So the appropriate choice of the first-line therapy strategy is very important. For the HR-positive metastatic breast cancer, we haven't strong data to head-to-head compare the chemotherapy with endocrine therapy as the first-line treatment. Methods: Two hundreds patients with HR-positive metastatic breast cancer were enrolled at 47 cancer centers in China from 2009 to 2012. Investigators decided to give chemotherapy or endocrine therapy according to their clinical judgements. Chemotherapy and endocrine therapy regimens followed the NCCN guildline. All the patiens haven't take any treatment after relapse or metastasis. All the patients were estrogen- receptor positive and/or progesterone-receptor positive,HER2 negative. Chemotherapy or endocrine therapy was continued in the progressive disease(PD) or unacceptable toxicity. Primary endpoint was progression-free survival(PFS), second endpoints were time to failure(TTF), response rate. Results: According to the investigator judgements, one hundred patient took chemotherapy(CT arm), another one hundreds patients took endocrine therapy(ET arm). Pt characteristics were balanced between the two arms: median age 49y/50y, median disease-free survival(DFS) 40m/30m, visceral/non-visceral metastatic 52%/40%. There was more patients with ≥2 metastatic sites in CT arm than ET arm (50% vs 32%). Following up to Dec 2012, reasons for early treatment discontinuation were : PD 25 pts, toxicity 38 pts in CT arm, PD 82 pts, toxicity 2 pts in ET ram. The median PFS was 52 weeks(95% CI 23.2-80.8 weeks) and 48 weeks(95% CI 38.9-57.0 weeks) for CT arm and ET arm(P = 0.589),respectively. The median TTF was 20 weeks and 48 weeks for CT arm and ET arm,respectively(P = 0.025). Response rate was 63% and 22% for CT arm and ET arm,respectively(P<0.001). But clinical benefit rate(CR+PR+SD≥6months) was 67% and 69% for CT arm and ET arm,respectively(P = 0.333). Subgroup analysis showed TTF were 48 weeks in ET arm and 15 weeks in CT arm(p = 0.038) for patients who had more than 2 years DFS. TTF results also indicated significant difference in single metastatic site pts and non-visceral metastatic pts between two arms. ET arm was superior to CT arm. Conclusions: Our results indicate first-line chemotherapy has higher response rate than first-line endocrine therapy for HR-positive meatstatic breast cancer, but chemotherapy has shorter maintaining therapy time. First-line endocrine therapy was more suitable than first-line chemotherapy for pts with DFS≥2y, single metastatic site and non-visceral metastatic. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-10-05.