Adherence to oral antineoplastic agents, an overview and meta-analysis

BACKGROUND: The use of oral antineoplastic therapies has accelerated in recent years. Non-supervised administration of oncological therapies introduces uncertainty in regard to adherence. This review and meta-analysis reports on available literature relating to adherence, adherence-measuring methods, interventions to improve adherence, and estimates patient adherence to common oral antineoplastic therapies. METHODS: A literature search was conducted in the PubMed database up to January 29, 2024 using relevant terminology for oral antineoplastic agents. Titles and abstracts of retrieved articles were screened, and full-text articles deemed of interest were reviewed. Studies suitable for meta-analysis and consistent with the analytical approach were selected based on adherence measurement methods and definitions. Random effects meta-analysis was conducted using the R package metafor and visualized with forest plots for cumulative adherence and lower-bound adherence separately. RESULTS: We identified eight reviews and 75 original studies on adherence to non-endocrine oral antineoplastic agents, spanning the years from 1987 to 2023, with the vast majority published from 2010 onward. This review estimates the cumulative adherence to oral antineoplastic agents to be 84% (95% CI, 78-89) and lower-bound adherence as 71% (95% CI, 63-78). CONCLUSION: The definition of non-adherence and the measurement methods used across studies vary, rendering the comprehensive understanding of the subject challenging. This review identifies an adherence rate that deviates from full compliance across a wide variety of treatment regimens and tumor types, which could provide valuable insights for healthcare professionals in optimizing patient management.