Abstract P2-08-66: Outcomes among metastatic breast cancer patients with characteristics that confer a less favorable prognosis

Abstract

Abstract Background: Recent advances in the treatment of hormone receptor positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (MBC) have contributed to increased overall survival (OS). Despite advances, MBC remains incurable and there is a subset of patients with clinical features that are associated with poorer prognosis. This study described the patient characteristics, treatment patterns, and outcomes of a cohort of US patients with HR+, HER2- MBC as a function of various factors associated with poor prognosis, including presence (vs. absence) of liver metastases (LM). Methods: This retrospective study used US community oncology electronic health record data from the Vector Oncology Data Warehouse. Eligible women who received systemic treatment for MBC, had a diagnosis of MBC in 2008 or later, and had completed at least three Patient Care Monitor (PCM) surveys, (a patient-reported outcomes survey collected as a part of clinical care), were included. OS was measured from the start of the first three regimen-based lines (1L, 2L and 3L) of treatment; patients without evidence of death were censored at the last observed visit. The statistical significance of differences in categorical and continuous variables between LM positive (LM+) and LM negative (LM-) were evaluated with chi-square (X2) tests, and t-tests, respectively. Kaplan-Meier and Cox analyses were applied to evaluate differences in OS by LM status and by line of therapy at the start of MBC treatment (unadjusted for treatment). Results: A total of 378 women, 98.4% residing in the South and 40.5% African-American, were included; 295 (78.0%) were LM- at the time of diagnosis. Following 1L, approximately 82.8% and 60.8% of patients received 2L and 3L, respectively. Patients with a LM+ status had a lower mean age (mean: 57.2, SD: 13.8 vs. 61.2, 13.1; p=0.016) and a higher percentage had a grade 3 tumor (36.1 vs. 24.7%; p=0.039) compared to patients with LM-status. Table 1 shows the OS results for 1L-3L. For all 3 lines, median OS for LM+ was shorter than the LM- median OS. LM+ patients had a poorer prognosis as they were more likely to have an OS event across 1L-3L compared to LM- patients. Conclusions: Among this community oncology cohort, median OS in 1L was 14 months shorter in LM+ patients compared to LM- patients. It is important to note that the sample size and selection criteria may limit generalizability of these results. Despite progress in treating women with MBC, treatment options are lacking for patients with less favorable prognosis, including those with LM. Other potential indicators of poor prognosis, such as high tumor grade, are being explored. Table 1.OS (months) by regimen-based line of therapy Measure Liver Mets (LM+) No Liver Mets (LM-) HR p-value 1L, # of Events/ # of Patients55/83168/295 Median (95% CI)23.9 (15.5-28.6)35.2 (30.1-42.3) <0.0001* Cox Hazard Ratio 1.93<0.0001 2L, # of Events/ # of Patients48/72149/241 Median (95% CI)16.6 (12.0-22.6)24.2 (21.3-29.0) 0.002* Cox Hazard Ratio 1.490.040 3L, # of Events/ # of Patients35/52118/178 Median (95% CI)11.5 (7.0-21.0)17.4 (14.7-20.0) 0.038* Cox Hazard Ratio 1.540.060CI=Confidence Interval; *p-value was derived using log rank test. Citation Format: Saverno K, Cuyun Carter G, Dufour R, Price G, Li L, DeLuca A, Nash Smyth E, Battiato L, Gable J, Walker MS, Huang Y-J, Hannas S, Schwartzberg LS. Outcomes among metastatic breast cancer patients with characteristics that confer a less favorable prognosis [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-08-66.