External validation of the American Joint Committee on Cancer melanoma staging system eighth edition using the surveillance, epidemiology, and end results program.

The discriminatory ability of AJCC-8 and AJCC-7 appear comparable. Changes in AJCC-8 identified stage IIID as a poor prognostic subgroup among stage III patients and elevated LDH in stage IV. However, patients with advanced T-stage, node-negative tumors experienced worse survival compared to those with earlier T-stage, node-positive tumors, and the results of ongoing trials should inform adjuvant therapy in this subset of patients.