Abstract P5-11-21: Retrospective analysis of first-line progression free survival compared endocrine therapy and chemotherapy inpatients with HR+/HER2-metastatic breast cancer

Abstract

Abstract Background: Endocrine therapy is preferred recommendation by clinical guidelines in premenopausal as well as postmenopausal women with hormone receptor(HR)-positive, HER2-negative metastatic breast cancer (MBC). However, in real-world clinical practice, chemotherapy was treated in the first-line in HR+/HER2- MBC, in particular aggressive tumor behavior and younger age. The aim of this retrospective study is to assess the clinical anti-tumor activity of endocrine therapy versus chemotherapy as first-line in HR+/HER2- MBC patients. Methods: This is a retrospective study of the first-line endocrine therapy compared with chemotherapy for hormone receptor-positive and HER2-negative MBC. 544 female patients were enrolled from Jan 2000 to Dec 2018 in Liaoning Cancer Hospital & Institute. The patients were hierarchical categoried as three cohorts: Only Endocrine Cohort (n=329), Only Chemotherapy cohort (n=159) and Sequential therapy of chemotherapy followed by endocrine therapy (n=56). Primary endpoint was Progression-Free Survival (PFS). Results: Among 544 patients enrolled, Median ages were 56, 51 and 53 in Only Endocrine Cohort (n=329), Only Chemotherapy cohort (n=159) and Sequential therapy (n=56), respectively. The proportion of premenopause was found equally in three arms (30%). 35.0%, 64.2% and 42.9% of patients had visceral metastases in only Endocrine cohort, only Chemotherapy and Sequential therapy. Median estimated PFS was superior in only endocrine cohort and sequential therapy than in only chemotherapy arm [19.0 months (95% CI: 16.4~21.6), 20.0 months (95% CI: 13.2~26.8) vs. 11.3 months (95% CI: 7.0~14.0), p = 0.000028 by log-rank (Mantel-Cox)]. Approximately 70% of the patients were post-menopause in the advanced setting (77.2% for only Endocrine, 68.6% for only Chemotherapy vs. 67.9% for Sequential therapy). In post-menopause, median PFS was longer in only Endocrine [20.0 months (95% CI: 8.3~15.7)] and Sequential therapy [20.0 months (95% CI: 12.8~27.2)] than that in only Chemotherapy cohort [12.0 months (95% CI: 13.2~26.8)]. The superior in PFS was similar in pre-menopause cohort [15.0 months (95% CI: 6.0~24.0), 20.0 months (95% CI: 11.1~28.9) vs. 7.0 months (95% CI: 4.3~9.7). Grade III or more hematologic toxicities were more common in only Chemotherapy and Sequential therapy than in only Endocrine therapy (67.2%, 64.3% vs. 25.8%). Conclusions: Endocrine therapy and Sequential therapy chemotherapy followed by endocrine therapy showed superior clinical benefit in terms of PFS compared with only chemotherapy as first-line in patients with HR+/HER2- MBC. Citation Format: Junnnan Xu, Tao Sun. Retrospective analysis of first-line progression free survival compared endocrine therapy and chemotherapy inpatients with HR+/HER2-metastatic breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P5-11-21.