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

Purpose: To construct an effective prognostic nomogram for patients with clinically localized Acral lentiginous melanoma (ALM). Methods: 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. Results: 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. Conclusion: A prognostic nomogram was established and validated to help predict the survival of ALM patients and guide individualized treatment strategies. [ABSTRACT FROM AUTHOR]