Environmental greenery and skin cancer risk: a prospective cohort study on incidence and mediating mechanisms.

BACKGROUND: Skin cancer, including malignant melanoma (MM) and non-melanoma skin cancer (NMSC), is a growing global public health problem. Green spaces are generally beneficial to public health, yet their impact on skin cancer risk remains contentious. METHODS: Using data from 318,738 participants in a large cohort, we examined the association between green space, domestic gardens, and natural environments within 300-m and 1,000-m buffer zones and skin cancer incidence. Hazard ratios (HRs) were estimated using Cox regression. Genetic susceptibility was assessed through polygenic risk scores, susceptible populations were identified through gene-environment interaction, potential biomarkers were discovered through metabolomics, and potential pathways were explored through mediator analyses. RESULTS: Domestic gardens are the main type of greenery associated with an increased risk of skin cancer. The highest quartile of exposure to gardens resulted in a 23% increased risk of developing MM (HR = 1.23, 95% CI: 1.08-1.41). People living within 300 m (HR = 1.10, 95% CI: 1.05-1.16) and 1,000 m (HR = 1.11, 95% CI: 1.06-1.17) of a garden had a higher risk of developing NMSC. Interaction analyses of domestic gardens with genetic characteristics showed that genetically susceptible, light-skinned, and sun-sensitive populations were at higher risk of cancer. Metabolomics identified metabolites (e.g., histidine) and NMSC markers (e.g., tyrosine) associated with MM. Unexpectedly, PM2.5 appeared to be a mediator of reduced skin cancer risk. CONCLUSIONS: We found that domestic gardens have a significant effect on skin cancer risk according to the type of greenery. Urban planning should target genetically and phenotypically susceptible populations with protective measures.