BACKGROUND: The literature surrounding survival of patients with multiple primary melanomas (MPM) yields variable and opposing findings, constrained by statistical challenges.
OBJECTIVES: To critically examine the available literature regarding survival of patients with MPM compared with single primary melanomas (SPM) and detail statistical methods employed.
METHODS: Electronic searches of Pubmed, Embase, Web of Science and Scopus, with cross-checking of references, for the period January 1956 - June 2019 were carried out. All studies published in English examining survival in patients with multiple melanoma were included. Case studies and small case series were excluded.
RESULTS: Fourteen studies were eligible for inclusion. Conclusions on survival varied markedly depending on the statistical method used. Four studies that accounted for survival bias by partitioning the survival time were included in the quantitative review, with three of these reporting a survival disadvantage for MPM, while the fourth showed no difference in survival. Pooled HR was 1.39 (1.07-1.81) but with significant heterogeneity (I2= 96.8% Phet < 0.001).
LIMITATIONS: Studies showed significant heterogeneity in methodology.
CONCLUSIONS: When data was analysed with robust statistical methods, patients with MPM had a survival disadvantage compared with patients with SPM.