The association between smoking and risk of skin cancer: a meta-analysis of cohort studies

Purpose The association between smoking and the risk of skin cancers has been studied without reaching consistent findings. This study aims to assess this association through an updated meta-analysis of cohort studies. Methods We retrieved cohort studies that investigated the temporal association between smoking and the risk of basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and malignant melanoma (MM). Pooled relative risks (RRs) and confidence intervals (CIs) of the included articles were calculated for current, former, and heavy smoking compared with never smoking. Publication bias was detected using the Egger's regression. Results A total of 15 studies, published between 1990 and 2018, were included. Current smoking was associated with a higher risk of SCC (pooled RR = 1.32, 95% CI 1.15, 1.52) but with a lower risk of BCC (pooled RR = 0.85, 95% CI 0.75, 0.96) and MM (pooled RR = 0.72, 95% CI 0.64, 0.82). No publication bias was detected, and no single study had a substantial impact on the pooled results. Similar results were detected for heavy smoking, while former smoking was not associated with the risk of skin cancer. Conclusion Current smoking and heavy smoking were associated with a higher risk of SCC but a decreased risk of BCC and MM, while former smoking was not associated with skin cancer risk.