Systemic therapy, survival and end-of-life costs for metastatic triple-negative breast cancer: retrospective SEER-Medicare study of women age ≥65 years.

To analyze therapy for metastatic triple-negative breast cancer (mTNBC), factors contributing to survival and costs. Using 2010-2016 SEER-Medicare data, we identified women (≥65 years) with mTNBC. Of 302 eligible patients, 152 (50%) received systemic therapy. In multivariable regression analyses, only age <75 years was associated with therapy receipt (odds ratio: 2.91; 95% CI: 1.79-4.74); and only systemic therapy significantly reduced risk of death (hazard ratio: 0.34; 95% CI: 0.26-0.44). Median overall survival was 13.4 (95% CI: 11.3-15.1) vs 3.3 months (95% CI: 2.7-3.9) in therapy vs no-therapy cohorts. Mean per-patient-per-month costs <30 days before end-of-life/follow-up were $14,100 and $15,600 (2019 USD), respectively. Poor outcomes and high costs indicate need for more effective mTNBC therapy.