Real-World Data on First-Line Treatment of Hormone Receptor-Positive, HER2-Negative, Metastatic Breast Cancer in...

Endocrine therapy (ET) plus CDK4/6 inhibitors has become the standard first-line therapy for hormone receptor-positive/HER2-negative metastatic breast cancer (MBC). Utilizing real-world data, we aimed to characterize treatment patterns, assess the impact of health insurance type, and evaluate outcomes among Brazilian MBC patients with this subtype treated in the first-line setting.

This is an observational retrospective study assessing female patients aged ≥ 18 years diagnosed with HR+/HER2- MBC between January/2018 and December/2020 at 13 sites in Brazil. The primary objective was to describe the treatment patterns within both the public and private healthcare systems. Secondary outcomes were progression-free survival (PFS) and overall survival (OS).

In total, 307 patients were included. The most frequent treatment was ET alone (42.4%), followed by chemotherapy (31.6%), and ET plus CDK4/6 inhibitors (25.1%). The greatest difference in access to treatment was observed in the use of ET plus CDK4/6 inhibitors between the private (48.3%) and public healthcare systems (2.6%), (P < .0001). Of the 84 patients that received CDK4/6 inhibitors, ribociclib was the most used (56.0%). With a median follow-up of 32.2 months (95% CI, 29.4-34.4), the median progression-free survival (PFS) was 24.2 months (95% CI, 18.6-30.4) in the public and 23.80 months (95% CI, 18.3-34.2) in the private healthcare system (P = .9294). The median OS was 52.7 months (95% CI, 49.4-NR) in the overall population.

ET remains the most used first-line treatment in Brazil. However, access to therapies varies significantly between public and private healthcare sectors. This disparity highlights inequality in access to treatment.