4-year overall survival after the introduction of adjuvant therapy for patients with stage III melanoma: A population-based study

Adjuvant systemic therapy for resected stage III melanoma was introduced in clinical practice following the improved recurrence free survival in randomized controlled trials. However, after ten years of follow-up, adjuvant treatment with dabrafenib plus trametinib did not result in a significant improvement in overall survival (OS). Currently, OS data for adjuvant anti-PD1 therapy are still pending.

In this retrospective nationwide population-based study, the 4-year OS was compared between patients who were diagnosed with stage III melanoma before and after the introduction of adjuvant therapy in the Netherlands. Propensity score matching (PSM) for age, sex, and four melanoma substages (IIIA-D) was applied to ensure comparability between the pre-adjuvant cohort, comprising patients diagnosed in 2015-2017, and the post-adjuvant cohort with patients diagnosed in 2019-2020.

A total of 2651 patients with stage III melanoma were included. The median follow-up for patients without an event was 89 months for the pre-adjuvant cohort and 49 months for the post-adjuvant cohort. After PSM, both cohorts consisted of 1215 patients. The 4-year OS rate was comparable between the pre-adjuvant and post-adjuvant adjuvant cohort (71.2 % vs. 73.8 %, HR=0.90, 95 % CI: 0.77-1.04). No significant difference in OS was observed between cohorts for the different substages of melanoma.

This population-based analysis of patients with stage III melanoma demonstrated no significant 4-year OS benefit after the introduction of adjuvant therapy. Pending the OS results of the randomized trials, the potential benefits and risks of adjuvant therapy should be carefully weighed for patients with stage III melanoma.