Real World Evidence on Hormone Receptor Positive and Human Epidermal Growth Factor Receptor 2 Negative Metastatic Breast Cancer in Italy: Insights From 2017 to 2021 Data.

Purpose: To describe patients with hormone receptor positive and human epidermal growth factor receptor 2 negative metastatic breast cancer (HR+/HER2- mBC) in Italy for demographic and clinical variables, comorbidity profile, metastases and therapeutic pathways. Patients and Methods: From 2017 to 2021, HR+/HER2- mBC patients were extrapolated from administrative databases of healthcare entities covering a catchment area of about 3 million health-assisted women. The study included patients with a hospital discharge diagnosis for mBC; Results: The study was focused on 6603 women with HR+/HER2- mBC subtype, at least two prior systemic therapies for metastatic status or at least one endocrine-based therapy, at least one taxane prescription and at least one CDK4/6 inhibitor prescription and at least 12-months of data available before and after inclusion. Mean age was 59 years; the most common pre-existing conditions were hypertension (53.7%), distantly followed by chronic obstructive pulmonary disease, diabetes and cardiovascular disease. The analysis of treatment patterns during follow-up, which considered 3-month or 6-month gaps for identification of two different aspecific chemotherapies, showed that 97% (N = 236) had a subsequent line and 86% (N = 211) a further treatment during follow-up. The most common prior anticancer treatments, found in almost all patients, were endocrine therapy and CKD4/6i, with 66% patients receiving an aspecific chemotherapy. Conclusion: This real-world analysis provides key insights into HR+/HER2- mBC in Italy, highlighting treatment patterns, rising diagnoses in younger women, and challenges in managing heavily pretreated patients. It emphasizes the need for further research on treatment sequencing, emerging therapies, and prior treatment duration to enhance clinical decision-making and patient care.