Meta-analysis of risk factors for cutaneous melanoma according to anatomical site and clinico-pathological variant

A systematic meta-analysis was performed to evaluate if cutaneous melanoma (CM) risk factors differ depending on body site and histological type. Adjusted estimates were extracted from 24 observational studies, for a total of 16,180 cases. Multivariate random-effects models were used to obtain summary relative risk (RR) estimates for all risk factors by body site and histological type. Summary RRs suggest that high naevus counts are strongly associated with CM on usually not sun exposed sites (p < 0.001) while different patterns of sun exposure show a tendency for higher RRs for CM on usually sun exposed sites than on other body sites (p = 0.087). Continuous pattern was found to be significantly inversely associated with CM for unexposed sites (p = 0.01). RRs also differed by body site for skin (p = 0.01) and hair colour (p = 0.01), and these differences could be attributed to gene variability. This finding seems to suggest different aetiologic pathways of melanoma development by anatomical site.