Abstract P3-08-55: Factors associated with prolonged post-recurrence survival in patients with postmenopausal estrogen receptor-positive breast cancer taking fulvestrant: A follow-up data of the JBCRG-C06 Safari study factors associated with prolonged post-recurrence survival in patients with postmenopausal estrogen receptor-positive breast cancer taking fulvestrant: A follow-up data of the JBCRG-C06 Safari study

Abstract

Abstract Background: To evaluate the survival risk is an important factor to decide or treatment options for recurrent breast cancer patients with estrogen receptor-positive (ER+) and human epidermal growth factor receptor 2 negative (HER2−), though there are not enough supporting reports from large-scale databases. The Safari study (UMIN000015168) is a newly conducted retrospective, multicenter cohort study including 1072 ER+ advanced breast cancer Japanese patients treated with fulvestrant 500 mg mostly as a second or later line hormonal therapy. The follow-up data of Safari study is evaluated to focus on any relationship between clinicopathological factors and post-recurrence survival (PRS) in ER+ HER2− recurrent breast cancer patients. Methods: PRS was defined as the duration from the date of initial treatment for recurrent breast cancer to death. The Cox hazards model was used to evaluate the relationship between the clinical factors and PRS. We also performed multivariate analysis on PRS using factors that showed a statistical difference (p < 0.15) in univariate analysis. Hazard ratios (HRs) with 95% confidence intervals (CIs) and p-values are described. All tests were two-sided and p<0.05 was considered statistically significant. Results: The main analysis was performed for 1031 cases (96.2%). Ninety four patients with HER2+ status and 53 patients with unknown HER2 status were excluded from this analysis. One hundred seventy-four cases with de novo metastatic or unresectable locally advanced disease were also excluded. Seven hundred ten patients were eligible for the PRS analysis. Median PRS was 7.0 years (95% CI: 6.4-7.6 years). In univariate analysis, the following factors were defined as associated with significantly longer PRS; younger age, earlier treatment line, longer the time from recurrent diagnosis to fulvestrant use, lower nuclear or histological grade (G1/G2/G3), no central nerve metastasis, chemotherapy as initial palliative systemic therapy, longer time to initial palliative chemotherapy, no prior perioperative chemotherapy, no prior perioperative hormonal therapy, and longer period after perioperative hormonal therapy to the diagnosis of recurrence. Recurrence cases after over 1-year perioperative hormonal therapy had better PRS than those after less than 1-year therapy. In multivariate analysis, the following factors were identified to be correlated with longer PRS (median 7.0 years); younger age (< 65 years; p = 0.0002), longer time (≥ 3 years) from recurrent breast cancer diagnosis to fulvestrant treatment (p< 0.001), low nuclear or histological grade (1/3; p< 0.001), chemotherapy as an initial palliative systemic treatment (p = 0.01), longer time to initial palliative chemotherapy (p< 0.0001), and no perioperative chemotherapy (p = 0.02). Kaplan-Meier curve showed that a longer time (≥ 1 year) to subsequent chemotherapy correlated positively with prolonged PRS (median PRS: 10.7 years, 95% CI 8.5-12.3 years vs. 6.3 years, 95% CI 5.9-6.8 years; p < 0.0001). Conclusions: In ER+ HER2− recurrent breast cancer patients who received fulvestrant as their initial or second line palliative treatment, the longer duration to initiate a subsequent chemotherapy positively correlated with longer PRS. Citation Format: Kenjiro Aogi, Hidetoshi Kawaguchi, Norikazu Masuda, Takahiro Nakayama, Keisei Anan, Yoshinori Ito, Shoichiro Ohtani, Nobuaki Sato, Shigehira Saji, Toshimi Takano, Eriko Tokunaga, Seigo Nakamura, Yoshie Hasegawa, Masaya Hattori, Tomomi Fujisawa, Satoshi Morita, Miki Yamaguchi, Hiroko Yamashita, Toshinari Yamashita, Yutaka Yamamoto, Daisuke Yotsumoto, Masakazu Toi, Shinji Ohno. Factors associated with prolonged post-recurrence survival in patients with postmenopausal estrogen receptor-positive breast cancer taking fulvestrant: A follow-up data of the JBCRG-C06 Safari study factors associated with prolonged post-recurrence survival in patients with postmenopausal estrogen receptor-positive breast cancer taking fulvestrant: A follow-up data of the JBCRG-C06 Safari study [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 P3-08-55.