How Strong Is the Link Between Merkel Cell Carcinoma and the Occurrence of Other Skin Cancer Types? A Meta-Analysis

This meta-analysis presents findings from nine studies involving 4626 cases of primary Merkel cell carcinoma (MCC), aimed at evaluating the relationship between primary MCC and the incidence of a second skin cancer. The analysis reveals a significant association, with a calculated risk ratio of 2.97 (95% CI, 1.70–5.19, p = 0.0001), indicating that individuals diagnosed with primary MCC are nearly three times more likely to develop the second skin cancer compared to patients with other second cancers. Among the second skin cancers analysed, basal cell carcinoma (BCC) showed the highest risk (0.69, 95% CI 0.35–1.37), followed by squamous cell carcinoma (SCC) (0.45, 95% CI 0.23–0.90) and melanoma (0.31, 95% CI 0.19–0.50). While geographic analysis showed that patients in Northern Europe have a non-significant 1.7-fold increased likelihood of developing the second skin cancer relative to those in North America (USA), where the likelihood of developing the second skin cancer is significantly lower at 0.7 times. The results underscore the importance of implementing enhanced surveillance and preventive strategies for individuals at increased risk. By identifying these associations, we may improve the early detection of the second skin cancer in patients with MCC.