Real-world treatment patterns of hormone receptor-positive and human epidermal growth factor receptor 2-negative advanced breast cancer

Introduction
The HABER study aimed to evaluate real-world treatment patterns for hormone receptor-positive, HER-2-negative (HR+/HER-2–) advanced breast cancer (ABC) in Poland, focusing on adherence to local and international guidelines.

Material and methods
This retrospective, non-interventional analysis included 440 patients treated between September 2020 and August 2021 across 17 clinical sites. The trial was registered with ClinicalTrials.gov, NCT05478590.

Results
Most patients were postmenopausal (76.7%) with a mean age of 62.7 years, and nearly two-thirds had comorbidities. Almost half of the patients (48.6%) were diagnosed with de novo ABC. CDK4/6 inhibitor-based therapies were the predominant first-line treatment (74.1%), aligning with guideline recommendations. These therapies were more frequently combined with aromatase inhibitors (64.7%) than with fulvestrant (35.3%). The mean age ± standard deviation of patients treated with endocrine therapy (71.8 ±11.6 years) was higher than the age at which they received CDK4/6 inhibitors with endocrine therapy (61.3 ±11.7 years) or chemotherapy (62.0 ±13.2 years), p < 0.0001. Patients treated with CDK4/6 inhibitor-based therapy had more often the Eastern Cooperative Oncology Group performance status of 0–1 (90.8%) than those receiving endocrine therapy (48.1%) or chemotherapy (56.7%). Chemotherapy was used primarily for rapid disease progression or life-threatening visceral crises. CDK4/6 inhibitors remained the preferred treatment across all metastatic sites.

Conclusions
Treatment choice was influenced by patient demographics, performance status, and time from early breast cancer to relapse. The observed treatment patterns of first-line treatment of HR+/HER– ABC are highly aligned with current national and international guidelines.