Adherence to Adjuvant Therapy in Patients with Resected Melanoma: An Application of the Theory of Planned Behavior

INTRODUCTION: Adherence to adjuvant therapy is crucial for effective disease management in patients with resected melanoma. This study assessed patient-reported adherence to adjuvant therapy and identified behavioral/belief constructs associated with adherence in patients with resected melanoma. METHODS: Patients with resected stage III/IV melanoma were recruited through the Melanoma Research Foundation and a patient panel to complete an online survey. Patient characteristics, medical history, and adherence to therapy were captured. In accordance with the theory of planned behavior (TPB), the survey measured behavioral, normative, and control beliefs, and intention to adhere to therapy. Structural equation modeling (SEM) examined their relationships with adherence. RESULTS: Among all patients who received adjuvant therapy and completed the survey (n = 184), 69% received intravenous and 31% received oral therapy; the majority (85.3%) were somewhat involved in deciding to start therapy. Mean age was 45 years, 44% of patients were female, and 83% had stage III/IV disease at diagnosis. Patients had a mean disease duration of 1.5 years, a time since complete resection of 10 months, and an adjuvant therapy duration of 8 months. Adherence to adjuvant therapy was high overall and higher with intravenous than with oral therapy (98.4% versus 91.2%, P = 0.002). All underlying TPB constructs were significant in the SEM model, which explained 60.3% of the variance in intention to adhere. Control beliefs had the strongest association with intention to adhere (standardized estimate = 0.47, P < 0.001) and intravenous therapy was associated with greater adherence than oral therapy (standardized estimate = 0.26, P < 0.001). CONCLUSIONS: This study found that patients with resected melanoma are highly engaged in the decision to initiate systemic adjuvant therapy, with an overall high adherence rate to prescribed adjuvant treatment. Enhancing patients’ view of their capability to adhere to treatments may further improve the adherence rate to melanoma adjuvant therapy.