Abstract P1-10-03: Real-world effectiveness outcomes by race in patients with metastatic triple negative breast cancer
Authors: Skinner KE , Dufour R , Haiderali A , Huang M , Schwartzberg LS 
Published: May 2019

Background: Age, race, and tumor environment are major contributors in the variance of treatment outcomes in patients (pts) with breast cancer. Few studies have evaluated outcomes in real-world pts to identify high-risk populations. We aimed to compare differences in effectiveness outcomes by race among pts with metastatic triple negative breast cancer (mTNBC).

Methods: This retrospective observational study evaluated effectiveness outcomes of progression-free survival (PFS) and overall survival (OS). Eligible pts were female, age ≥18 years, and diagnosed with mTNBC between 1/1/2010 and 1/31/2016 from 9 US community oncology practices. The sample was stratified by race (White, African-American [AA], Other). Kaplan-Meier methods were used to describe time-to-event outcomes. Cox regression models were used to examine the effect of race-based groups on PFS and OS.

Results: The study included 608 pts (60.2% White, 33.9% AA, 5.9% Other; mean [standard deviation] age 57.5 [13.5] years). Pt characteristics largely did not differ across groups, except AA pts appeared younger (AA: 55.3 years vs. White: 58.6 vs. Other: 58.6, p=0.015) and less likely to have brain metastasis (AA: 8.3% vs. White: 15.0% vs. Other: 19.4% p=0.034). 505 pts (83.1%) received anti-cancer treatment (treated) following mTNBC diagnosis, while 103 pts (16.9%) did not receive anti-cancer treatment (untreated). The prognosis for untreated pts who did not receive anti-cancer therapy was poor, with a median OS of 4.8 months from mTNBC diagnosis compared to 12.8 months for treated pts (p=0.030). The proportion of treated pts did not differ by race (AA: 85.0% vs. White 82.5% vs. Other: 77.8%, p=0.518). Treatment class also did not differ by race (p=0.861), with Taxane therapy being the most common treatment. Among treated pts, median PFS and median OS from the start of first line treatment were 4.2 months and 12.0 months, respectively (Table 1). AA pts had a poorer prognosis than White pts as they were more likely to have a PFS event and also more likely to have an OS event compared to White pts (Hazard Ratio [HR]: 1.24, p=0.042; HR: 1.35, p=0.006; respectively).

Conclusions: This evaluation of effectiveness outcomes indicates high unmet need as 1 in 6 mTNBC pts did not receive anti-cancer treatment. Furthermore, AA race was associated with poor outcomes. AA pts had shorter PFS and OS than other pts, and were more likely to experience progression or death than White pts.; despite being younger and less likely to have brain metastasis, which are typically associated with better outcomes. Future studies should be conducted to address unmet need and health outcome disparities in high-risk populations.

Table 1.Effectiveness Outcomes by Race among Treated Pts WhiteAAOtherOverallp-value*PFS, # of events/# of pts267/302163/17526/28456/5050.193PFS, Median (95% CI of Median)4.37 (3.91-5.06)3.78 (3.12-4.34)4.21 (2.24-6.12)4.18 (3.72-4.57) OS, # of events/# of pts235/302155/17520/28410/5050.004OS, Median (95% CI of Median)13.74 (12.03-16.50)9.34 (7.69-10.95)10.42 (6.58-19.89)11.97 (10.26-13.38) AA African-American; CI confidence interval; PFS progression-free survival; OS overall survival; *p-value was derived using log rank χ 2 to evaluate differences across race groups

Citation Format: Skinner KE, Dufour R, Haiderali A, Huang M, Schwartzberg LS. Real-world effectiveness outcomes by race in patients with metastatic triple negative breast cancer [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 P1-10-03.