Introduction:
The systemic immune-inflammation index (SII), based on peripheral lymphocyte, neutrophil, and platelet counts, has recently been investigated as a prognostic marker in several tumors. However, the SII has rarely been reported in skin cancers. In this study, we aimed to assess the association between SII values and the risk of occurrence of skin cancers.

Material and methods:
This cross-sectional study was based on National Health and Nutrition Examination Survey data from 2010 to 2018 and involved 32,012 participants. The SII was calculated as the platelet count × neutrophil count/lymphocyte count. A weighted multivariate logistic analysis was conducted to examine the relationship between SII values and the occurrence of skin cancers. In addition, a subgroup analysis and a sensitivity analysis were conducted to identify underlying moderators and the stability of the relationship, respectively.

Results:
Compared with participants in the lowest quartile of SII values, the odds ratios for non-melanoma skin cancer were 1.650 (95% CI: 1.158–2.352) for participants in the quartile with the highest SII values after multivariate adjustments. In subgroup analyses, we found significant interactions between log-transformed SII values and age (p < 0.001 for interaction), race (p < 0.001 for interaction), education level (p < 0.001 for interaction), marital status (p < 0.001 for interaction), and annual household incomes (p < 0.001 for interaction) in the association with non-melanoma skin cancer.

Conclusions:
Our findings suggest a positive association between high SII values and skin cancers in the U.S. population. Age, levels of education, marital status, and annual household incomes affect the positive association between high SII values and non-melanoma skin cancers.