Background: Metastatic HR+/HER2- breast cancer is commonly treated with CDK4/6 inhibitors in combination with endocrine therapy. However, the efficacy and safety of this approach in elderly patients (≥70 years) remain unclear, particularly in the context of real-world clinical practice. This study aims to evaluate the clinical outcomes and tolerability of CDK4/6 inhibitor treatments in this fragile population, which is often under-represented in randomized clinical trials.
Patients and methods: This retrospective multicenter study included elderly patients with metastatic HR+/HER2-negative breast cancer receiving first-line CDK4/6 inhibitors. The primary endpoint was progression-free survival (PFS). The secondary endpoints focused on the overall survival (OS), safety, and tolerability, considering variables such as tumor subtype, age, comorbidities, and treatment specifics.
Results: The median PFS and OS were slightly lower than those reported in clinical trials, reflecting the inclusion of a more fragile population. The luminal B subtype was linked to a poorer PFS, while other factors like age, BMI, and ECOG status did not significantly affect the outcomes. A safety analysis indicated a higher incidence of grade 3 or higher toxicities, especially in frail patients, leading to dose reductions. Despite these challenges, CDK4/6 inhibitors were generally well-tolerated, allowing most patients to continue therapy.
Conclusions: CDK4/6 inhibitors with endocrine therapy are effective in elderly patients with metastatic HR+/HER2- breast cancer, though careful management is crucial to balance efficacy and minimize adverse events.
Keywords: CDK4/6 inhibitors; HER2-negative; elderly patients; hormone receptor-positive; metastatic breast cancer; real-world data; retrospective study.