Differences in the demographics, incidence, and survival of palmar and plantar acral melanoma: a population-based study.

ABSTRACT

Acral melanoma (AM) has the worst prognosis of all cutaneous malignant melanomas (CMM). Differences between palmar and plantar tumors have not been well characterized at the population level. The objective of this study was to investigate the differences in demographics, incidence, and survival between palmar and plantar AM. The 2004-2016 National Cancer Database (NCDB) and 2000-2018 Surveillance, Epidemiology, and Results (SEER) databases were used to evaluate differences between palmar and plantar AM. Data were analyzed using Chi-square test, Fisher's exact, T-test, or likelihood ratio test. A total of 5002 participants were included in the study. A greater percentage of tumors occurred on the plantar surface (82.0%) than the palmar surface (18.0%). The incidence of plantar tumors is four times greater than palmar tumors (1.7 vs 0.4 cases per 1,000,000 people per year). Palmar melanomas were more likely to occur in Whites (84.6% vs 76.8%, p < 0.001) and be treated with amputation (28.1% vs 12.9%, p < 0.001) compared to plantar melanomas. Disease-specific five-year survival was similar for all palmar (80.8%) and plantar tumors (78.2%). While subtle differences do exist between palmar and plantar tumors, they behave similarly overall and should be treated as one entity.