Acral lentiginous melanoma: clinicopathological characteristics and survival outcomes in the US National Cancer Database 2004–2016

Funding sources: none. Conflicts of interest: the authors declare they have no conflicts of interest. Dear Editor, Acral lentiginous melanoma (ALM) is one of four subtypes of cutaneous melanoma (CM), comprising 2–3% of all melanomas in the USA.1 It occurs predominantly on the palms, soles and nail beds. It is a common subtype found in people with darker skin types. ALMs are generally associated with a poor prognosis.2 Understanding of the demographics, outcomes and treatment of this type of melanoma can be aided by studying a larger cancer registry.3 This study, to our knowledge the largest retrospective study of ALM, aims to take a closer look at the difference in demographics and overall survival (OS) of patients with ALM. The National Cancer Database (NCDB) was queried for all patients with ALM from 2004 to 2016. The NCDB gathers information from more than 1500 accredited cancer facilities in the USA and Puerto Rico. It collects approximately 70% of cancer diagnoses in the USA annually.4 To reduce ambiguity, only patients with histologically confirmed cases of ALM as the primary malignancy were included. Only cases in the upper extremities, including the palms and fingernails, and in the lower extremities, including the soles and toenails, were included. Univariate relationships between overall mortality from ALM and known and suspected prognostic variables were assessed using the Kaplan–Meier (KM) method. Variables that showed significant differences (P < 0·05) on univariate KM analysis, including age, sex, race, Charlson/Deyo comorbidity (CDCC) index, stage, ulceration, Breslow thickness, income status, facility type, primary site, insurance status and treatment type, were included in the Cox regression. As this study included no patient identifiers, it was exempted by the Institutional Review Board.