OBJECTIVES: To describe real-world treatments, disease progression, and survival in patients with HR+/HER2- locally advanced unresectable or metastatic breast cancer (ABC) in Latin America.

METHODS: We conducted a retrospective medical record review of patients who initiated treatment for HR+/HER2− ABC from 01/2012 to 05/2014 at 15 hospitals in Latin America. Disease characteristics, treatments, and clinical outcomes were abstracted from patient records from 12/2016 to 12/2017. Data from Mexico were excluded from Kaplan-Meier progression-free survival (PFS) and overall survival (OS) due to incomplete event information.

RESULTS: Of the 806 selected patients, 575 (71.3%) were initially diagnosed with stage IIIB/IIIC/IV disease while 231 (28.7%) progressed to ABC from an earlier stage. The mean age at ABC diagnosis was 58 years. Nearly half of patients had bone metastasis; 286 (35.5%) had visceral disease. In first-line treatment, 386 (47.9%) patients received endocrine therapy alone (ET), 305 (37.8%) received chemotherapy alone (CT), and 115 (14.3%) received other combinations. During follow-up, 528 (65.5%) patients initiated second-line therapy. Among them, 340 (64.4%) received ET, 153 (29.0%) received CT, and 35 (6.6%) received other combinations. In first-line, median (95% CI) PFS was 7.1 months (5.1-11.7) on CT; 17.0 months (14.2-19.7) on ET. In second-line, median (95% CI) PFS was 7.1 months (5.1-8.0) on CT; 10.0 months (7.9-13.2) on ET. Disease progression was the top reason for discontinuing first- and second-line therapy (283 [35.1%] and 191 [36.2%], respectively). Median OS (95% CI) from first-line initiation was 2.7 years (2.0-3.2) on CT; 4.4 years (3.9-unestimable) on ET.

CONCLUSIONS: Although ET is typically recommended for HR+/HER2− ABC, a substantial proportion of patients received CT. PFS and OS were longer among patients receiving ET than those receiving CT, possibly related to characteristics of patients selected for these treatments, different treatment effects, or both. Findings indicate a need for alternative treatments that could extend PFS and OS.