Abstract: 【Abstract】 Objective To investigate prognostic factors for acral lentiginous melanoma （ALM）, and to construct a nomogram to verify the predictive value of these factors. Methods Clinical data on 1 573 patients with ALM were collected from the Surveillance, Epidemiology, and End Results （SEER）database of National Cancer Institute in United States between 2004 and 2015. Data about patients′ age, gender, ulcer status, SEER staging, surgical protocols, T-, N- and M-staging, overall survival rates and disease-specific survival rates were extracted. Chi-square test was used to analyze the correlation of clinical characteristics with overall survival rates and melanoma-specific survival rates, and univariate and multivariate Cox proportional hazards regression models were used to investigate prognostic factors and establish predictive models. Results Among the 1 537 patients with ALM, 714 were males, 823 were females, 818 were under 64 years of age, and 1 363 were Caucasian. Skin lesions occurred on the lower limbs and buttocks in 1 205 cases, and 974 cases had no ulcers; according to the SEER staging, non-spread localized skin lesions were observed in 1 048 cases. There were significant differences in the mortality rate among patients with different ages at diagnosis, of different gender, ulcer status, surgical status, and at different SEER stages, T-, N- and M-stages （all P < 0.001）. Univariate and multivariate Cox regression analysis showed that age ≥ 65 years, male, ulcers and distant lymph node metastasis in the SEER staging were associated with increased risk of death in the patients （all P < 0.05）, and the mortality rate was significantly higher in the patients with T2-, T3- or T4-stage ALM than in those with T1-stage ALM （all P < 0.05）, and higher in the patients with N1-, N2- and N3-stage ALM than in those with N0-stage ALM （all P < 0.05）. Conclusion Age, gender, ulcer status, SEER stages, T- and N-stages are independent prognostic factors for overall survival rates and disease-specific survival rates of ALM.

Key words: Melanoma, Acral lentiginous melanoma, SEER program, Prognostic factors