Differences in Preferences for Drug Therapy Between Patients with Metastatic Versus Early-Stage Breast Cancer: A Systematic Literature Review.

Introduction: Compared with early stages (eBC) metastatic BC (mBC) is incurable. In mBC, aggressive treatment may increase the duration of survival but may also cause severe treatment side effects. A better understanding how patients with BC value different aspects of drug therapy might improve treatment effectiveness, satisfaction and adherence. This systematic review aims to identify and summarise studies evaluating patient preferences for drug therapy of BC and to compare preferences of patients with eBC and mBC.

Methods: The systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The electronic databases PubMed and Web of Science were searched on 22 June 2023. All studies published to this point were considered. Original studies reporting patient preferences on BC drug therapy determined by any type of choice experiment were eligible. A narrative synthesis of the effect measures presented as relative importance ratings, trade-offs (required benefit to make a therapy worthwhile) or monetary values of the treatment attributes was reported for each study. Risk of bias assessment for individual studies was performed using the checklist for observational studies from the STROBE Statement and the checklist from 'Conducting Discrete Choice Experiments to Inform Healthcare Decision Making: A User's Guide'. The study protocol was registered at the PROSPERO database (CRD42022377031).

Results: A total of 34 studies met the inclusion criteria were included in the analysis evaluating the preferences of patients with eBC (n = 18), mBC (n = 10) or any stage BC (n = 6) on, for example, chemotherapy, endocrine therapy, hormonal therapy or CKD4/6-inhibitors using different types of choice experiments. Regardless of the stage, most patients valued treatment effectiveness in terms of survival gains higher than potential adverse drug reactions (ADRs). Treatment cost, mode of administration, treatment regimen and monitoring aspects were considered as least important treatment attributes. In addition, preferences concerning 16 different types of ADRs were described, showing high heterogeneity within BC stages. Yet, comparable results across BC stages were observed.

Conclusions: Regardless of the stage, patients with BC consistently valued survival gains as the most important attribute and were willing to accept the risk of potential ADRs. Incorporating patient preferences in shared decision making may improve the effectiveness of interventions by enhancing adherence to drug therapy in patients suffering from BC.