Drug-related problems, adherence and quality of life in outpatients receiving endocrine treatment for hormone receptor-positive breast cancer: A prospective study

Introduction Patients receiving long-term endocrine treatment (ET) for hormone receptor-positive breast cancer commonly use supportive-care and concomitant medicines, resulting in complex regimens with greater risks of drug-related problems (DRPs) and non-adherence. This study quantified DRPs per patient and assessed their management, potential drug–drug interactions, ET adherence, and within-patient quality-of-life (QoL) changes. Methods This prospective, single-centre, single-arm pre–post study included 95 outpatients receiving ET. A clinical pharmacist reviewed medication regimens, classifying DRPs and interventions with Pharmaceutical Care Network Europe V9.0. Assessments included Micromedex screening for potential interactions, the 8-item Morisky Medication Adherence Scale for adherence, and the European Organisation for Research and Treatment of Cancer QLQ-C30 and QLQ-BR23 for QoL at baseline and 2 months. Results Overall, 287 DRPs were identified in 88 patients (92.6%; 3.02 ± 1.77 per patient): 15 (5.2%) involved ET, 118 (41.1%) supportive-care medicines, and 154 (53.7%) other concomitant medicines. Of 688 interventions, 686 (99.7%) were accepted, while 142 DRPs (49.5%) were completely resolved. Potential interactions were detected in 54 patients (56.8%); 54/110 (49.1%) were major. Low ET adherence was identified in 50/93 patients (53.8%). Among 85 patients with paired QoL data, global health/QoL and functional scores increased significantly. Higher DRP counts correlated with poorer QoL, whereas higher adherence correlated with lower symptom burden. Conclusions DRPs extended beyond ET to patients’ complete medication regimens. Despite high intervention acceptance, complete resolution was less frequent. Controlled multicentre studies with longer follow-up are needed to evaluate the effects of clinical pharmacist-led care on DRP resolution, ET adherence, and QoL.