Persistence to palbociclib treatment in HR+/HER2- breast cancer patients: A real-world study

ObjectiveTo evaluate adherence and persistence to palbociclib treatment in patients with advanced HR+/HER2- breast cancer in real-world clinical practice.MethodsThis observational, retrospective study was conducted using electronic medical records from two regional hospitals. Patients with locally advanced or metastatic HR+/HER2- breast cancer who initiated palbociclib treatment between January 2017 and December 2024 were included. Adherence was assessed using the medication possession ratio (MPR), and persistence was evaluated through the Kaplan-Meier method.ResultsEighty-two patients were included, with a median age of 69 years. Treatment adherence was 92.7% (MPR ≥80%). Median treatment persistence was 40.9 months (IQR: 3.3), with rates of 83.2% at 6 months, 72.2% at 12 months, and 57.9% at 24 months. A total of 47.6% of patients discontinued treatment, mainly due to disease progression (37.8%) or toxicity (9.8%). The most frequent adverse events were neutropenia (72.0%) and anemia (63.3%).ConclusionsPalbociclib demonstrated high adherence and persistence in real-world clinical practice, with a discontinuation rate comparable to that of previous clinical trials.