Impact of adjuvant therapy on melanoma-specific survival in elderly patients with high-risk resected melanoma: a multicenter international retrospective study

Purpose Adjuvant systemic therapy improves recurrence-free survival in resected high-risk melanoma, but elderly patients remain markedly under-represented in clinical trials; their competing risk of death from other causes needs to be considered. Consequently, the clinical benefit of adjuvant therapy in older populations remains uncertain. We conducted an international real-world study to evaluate survival outcomes of patients aged ≥75 years with resected stage III-IV melanoma managed with adjuvant systemic therapy or observation. Methods In this multicenter retrospective cohort study, patients aged ≥75 years with completely resected stage III-IV cutaneous melanoma were identified across 14 international melanoma centers. Patients received either standard adjuvant systemic therapy (anti-programmed cell death protein 1 immunotherapy or BRAF/MEK-targeted therapy) or observation. The primary endpoint were melanoma-specific survival (MSS) and overall survival (OS). Secondary endpoints included recurrence-free survival (RFS). Survival outcomes were estimated using Kaplan-Meier methods and evaluated with multivariable Cox regression models adjusted for age, stage, sex, and mutation status. Results A total of 580 patients were included (median age 79 years; range, 75–99), of whom 222 (38%) received adjuvant therapy and 358 (62%) underwent observation. Adjuvant therapy was associated with significantly improved MSS, with 5-year MSS of 74% compared with 60% in the observation group (adjusted HR 0.58; 95% CI 0.40 to 0.85; p=0.005), as well as OS (adjusted HR 0.66, 95% CI 0.51 to 0.87; p=0.002). Adjuvant therapy was also associated with improved RFS (HR 0.57, 95% CI 0.45 to 0.72; p<0.0001). Among patients managed with observation, disease recurrence occurred in 69%, yet only 47% of those patients received systemic therapy as first-line management of recurrence. Notably, among observation patients who remained recurrence-free or received systemic therapy after recurrence, MSS was comparable to that observed in adjuvant-treated patients (HR 0.83; 95% CI 0.55 to 1.25). Conclusion In this large international real-world cohort of elderly patients with resected melanoma, adjuvant therapy was associated with clinically meaningful improvements in MSS, OS and RFS. Although immunotherapy retained efficacy when administered at recurrence, many elderly patients did not receive systemic therapy as first-line management of recurrence. Adjuvant therapy may therefore represent an important strategy to ensure timely access to effective treatment in carefully selected older patients.