Adherence to High Cost Oral Antineoplastic Drugs in Oncological Patients of Arturo López Pérez Foundation Oncological Institute: An Observational Study

BACKGROUND Cancer remains a major global public health challenge, with incidence and treatment costs steadily increasing. The use of oral antineoplastic drugs (OAD) has expanded due to their convenience and positive impact on patients’ quality of life, but ensuring optimal adherence remains a critical issue. Non-adherence can compromise treatment effectiveness, increase healthcare costs, and worsen clinical outcomes. This study aimed to evaluate adherence to high-cost oral anticancer drugs (HCOADs) among oncological patients from Arturo López Pérez Foundation Oncological Institute, and to explore its association with demographic and clinical characteristics as well as progression-free survival (PFS). METHODS A prospective observational study was designed with a 12-month follow-up period. Patients enrolled in the Oncological Insurance (OI) of Arturo López Pérez Foundation Oncological Institute who received HCOADs between 2020 and 2021 were included. Adherence was assessed monthly through the telephone administration of the Simplified Medication Adherence Questionnaire (SMAQ). Demographic and clinical variables, as well as relevant clinical outcomes (disease progression, adverse events, and mortality), were collected. Descriptive and survival analyses (Kaplan–Meier) were performed RESULTS Out of ninety-two eligible patients, forty-nine participated in the study (53.3%). All participants maintained full adherence throughout the follow-up period. However, 36.7% experienced disease progression, 4.1% developed treatment-related toxicity, and 4.1% died. The 12-month PFS rate was 50%. A marked increase in progression was observed after the seventh month. No statistically significant associations were found between adherence and clinical outcomes. CONCLUSION Full adherence may be influenced by financial support and personalized follow-up. Nevertheless, the observed disease progression suggests that adherence alone is not sufficient to ensure favorable outcomes. A comprehensive approach that incorporates additional clinical and social determinants is warranted.