Previous studies have identified an inverse association between melanoma and smoking; however data from population based studies are scarce.

To determine the association between smoking and socioeconomic status on the risk of development of melanoma. Furthermore, we sought to determine the implications of smoking and socioeconomic status on survival.

We conducted a population-based case-control study. Cases were identified from the Welsh Cancer Intelligence and Surveillance Unit (WCISU) during 2000-2015 and controls identified from the general population. Smoking and socioeconomic status were obtained from data linkage with other national databases. The association of smoking status and socioeconomic status on the incidence of melanoma were assessed using binary logistic regression. Multivariate survival analysis were performed on a melanoma cohort using Cox proportional hazard model using survival as the outcome.

During 2000-2015, 9,636 patients developed melanoma. Smoking data were obtained for 7,124 (73.9%) of these patients. 26,408 controls were identified from the general population. Smoking was inversely associated with melanoma incidence (Odds Ratio (OR) 0.70 95% CI 0.65 -0.76). Smoking was associated with an increased overall mortality (Hazard Ratio (HR) 1.30 95% CI 1.09-1.55), but not associated with melanoma specific mortality. Patients with higher socioeconomic status had an increased association with melanoma incidence (OR 1.58 95% CI 1.44-1.73). Higher socioeconomic status was associated with an increased chance of both overall (HR 0.67 95% CI 0.56-0.81) and disease specific survival (HR 0.69 95% CI 0.53-0.90).

Our study has demonstrated that smoking appeared to be associated with reduced incidence of melanoma. Whilst smoking increases overall mortality, no association was observed with melanoma-specific mortality. Further work is required to determine if there is a biological mechanism underlying this relationship or an alternative explanation, such as survival bias.