A novel survival nomogram for stage I-III acral lentiginous melanoma patients, based on the SEER database and a multi-center external validation cohort

To construct an effective prognostic nomogram for patients with clinically localized Acral lentiginous melanoma (ALM).

This retrospective study included ALM patients from the Surveillance, Epidemiology, and End Results (SEER) database from 2004–2015. The 1686 cases were divided into the training and internal validation cohorts at a ratio of 7:3. The Cox regression analyses were performed to select risk factors for the nomogram. The performances of the nomogram were evaluated using the concordance index (C-index), area under receiver operating characteristic curve (AUC), and calibration plots, and validated in an external multicenter cohort.

Age, gender, race, and stage were significantly associated with overall survival (OS), with a C-index of 0.727 and 0.722 in the training and internal validation groups, respectively. The AUC of 2-,4-, and 6 years were higher than or equal to 0.75. Age, gender, race, site, and stage were related to ALM patients' CSS which have better C-index of 0.791 and 0.774 in the training and internal validation set. The AUC of 2-,4-, and 6- were higher than or equal to 0.80. Both survival calibration curves of 2-,4, and 6-year OS and CSS brought out a good consistency. The external multicenter cohort authenticated the value of the nomogram of OS, with a C-index of 0.657 and an AUC of 0.67, 0.72, and 0.65 at 2, 4, and 6 years. Good consistency was also observed.

A prognostic nomogram was established and validated to help predict the survival of ALM patients and guide individualized treatment strategies.