Identifying high-risk features and improving follow-up strategies in thin melanoma: a retrospective cohort study

Thin melanomas (TMs) are typically associated with favourable outcomes, but a subset of patients experience recurrence and worse survival. Prognostic factors for recurrence in TM remain inadequately characterized.

To identify clinical and histopathological factors associated with recurrence and explore implications for follow-up strategies in TM.

A retrospective cohort study included 308 patients with TM (Breslow thickness 0.1-1 mm) treated at two medical institutions between 1998 and 2017. Patients were stratified into groups with recurrence (n = 53) and no recurrence (n = 255). Clinical and histopathological variables were analysed, and survival outcomes were assessed.

Recurrence (vs. no recurrence) was associated with nodular histology (13% vs. 3.1%, P = 0.02), presence of ulceration (17% vs. 2.7%, P < 0.001) and higher mitotic rate (mean 2.1 vs. 0.6 mitoses mm-2, P < 0.001). Ultrathin melanoma (Breslow ≤ 0.5 mm) was protective against recurrence (hazard ratio 0.08, P < 0.001). Recurrence (vs. no recurrence) reduced 10-year overall survival (62% vs. 95.7%, P < 0.001) and melanoma-specific survival (64% vs. 100%, P < 0.001).

Prognostic factors such as ulceration, mitotic rate and histological subtype should guide individualized follow-up strategies. Ultrathin melanomas may require less intensive monitoring, while melanomas > 0.5 mm could benefit from extended follow-up beyond current guidelines. Tailoring surveillance based on recurrence risk could improve outcomes and quality of care for patients with TM.