Abstract P1-09-09: Role of endocrine therapy in premenopausal patients with hormone receptor-positive metastatic breast cancer, compared with postmenopausal patients: Diachronic analyses from nationwide cohort in Korea (KCSG BR 14-07)
Authors: T-Y Kim, J-H Ahn, JH Yoon, JH Sohn, GM Kim, KH Lee, YH Park, S-J Koh, SE Lee, Y Chae, KS Lee, KE Lee, HS Won, JH Kim, J Jeong, KH Park, EK Cho, Y-H Im, S-A Im, KH Jung
Journal: Cancer Research (2016)

Abstract Background Endocrine therapy (E) has a major role in treatment of hormone receptor (HR)-positive metastatic breast cancer (MBC). However, in contrast to western countries, premenopausal patients (PRE) more prevalent (50% of all breast cancer patients) and have less options of E than postmenopausal patients (POST) in Korea where the use of LHRH agonist in combination aromatase inhibitors (AIs) in PRE is restricted. Recently we have been successfully established nationwide cohort for the patients MBC (575 patients from 26 institutes). This study was designed to evaluate the role of E especially in PRE. Methods The patients with MBC were prospectively or retrospectively enrolled between September 2014 and May 2015. Only menopausal status-confirmed patients (296) were analyzed. Postmenopause was defined, based on NCCN guideline. Total duration of treatment was defined as the time from start day of any first treatment to end of any last treatment. Total duration of E was defined as the sum of time duration of each E. Overall survival was calculated from the start day of any treatment for MBC to any causes of death. This work is supported by National Strategic Coordinating Center for Clinical Research (H110C2020). Results A total of 296 patients with HR-positive MBC were analyzed [PRE, 169 (57.1%) and POST, 127 (42.9%)]. Except age (mean 44 and 60 years), baseline characteristics including in pathology, HER2 status, initial pathologic stage, de novo metastasis versus recurrence, surgery and adjuvant treatment (chemotherapy, endocrine therapy and radiotherapy) were well balanced. 92 (54.4%) of PRE and 77 (60.6%) of POST received at least one or more E through all treatment course. 41 (24.2%) of PRE and 44 (34.6%) received E as 1st-line treatment (p=0.034). Among PRE who received 1st-line of E, 30 (71.4%) and 9 (21.4%) of PRE received 2nd- and 3rd-line E. 20 (45.4%) and 10 (22.7%) of POST received 2nd- and 3rd- or more line of E. Most of PRE (54%) received tamoxifen+/-goserelin and 32% of PRE received AIs along with ovarian suppression. 71% of POST received AIs. As initial treatment, E was more frequently used in POST than in PRE (34.6% and 24.3%, p=0.053). Overall survival (OS) of all patients was 18.2 months (95% CI, 14.8-21.5). There was no difference in OS between PRE (17.8 months, 10.9-24.8) and POST (18.5 months, 95% CI, 13.2-23.9) (P=0.337). No difference of OS was observed (E, 18.1 moths, 95% CI, 13.0-23.3; chemotherapy 21.2 moths, 95% CI, 16.8-25.5), regardless of initial treatment. Total duration of treatment of PRE and POST were 15.2 and 13.6 months, respectively with no significant difference (p=0.389). PRE (8.3 moths, 95% CI,5.7-10.8) showed the trend toward longer duration of E in comparison with POST (5.5 moths, 95% CI,4.4-6.7), however the difference did not reach statistical significance (p=0.051). Conclusion E was more commonly used as 1st-line therapy in POST than in PRE. Although PRE had limited options of E, E was used in long duration of treatment especially in PRE. These findings suggested that E had a role in treatment for PRE with HR-positive MBC and could be used in treatment for PRE with good efficacy. Citation Format: Kim T-Y, Ahn J-H, Yoon JH, Sohn JH, Kim GM, Lee KH, Park YH, Koh S-J, Lee SE, Chae Y, Lee KS, Lee KE, Won HS, Kim JH, Jeong J, Park KH, Cho EK, Im Y-H, Im S-A, Jung KH. Role of endocrine therapy in premenopausal patients with hormone receptor-positive metastatic breast cancer, compared with postmenopausal patients: Diachronic analyses from nationwide cohort in Korea (KCSG BR 14-07). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-09-09.