Cumulative Erythemal Ultraviolet Radiation and Risk of Cancer in 3 Large US Prospective Cohorts.
Level 3 - non-randomized controlled study
Pooled analysis of three prospective cohort studies
PubMed 35671977 · doi:10.1093/aje/kwac101
What was done
Data from 3 prospective US cohorts—the Health Professionals Follow-up Study (47,714 men) and Nurses' Health Study I and II (212,449 women)—were analyzed to assess the relationship between cumulative erythemal ultraviolet radiation (UVR) and incident cancer risk (excluding nonmelanoma skin cancer). Cumulative UVR exposure was estimated using a validated spatiotemporal model based on residential history. Hazard ratios were estimated using multivariable-adjusted Cox proportional hazards models comparing UVR quintiles against the lowest quintile.
What was found
Compared with the lowest quintile of UVR exposure, the highest quintile had a small increase in the risk of any cancer (hazard ratio [HR] = 1.04, 95% CI: 1.01, 1.07; P for heterogeneity = 0.41). All UVR quintiles showed similar small increases in the risk of any cancer when excluding melanoma. Erythemal UVR was positively associated with melanoma (highest quintile HR = 1.17, 95% CI: 1.04, 1.31; P for heterogeneity = 0.83).
Why it matters
These findings do not support the hypothesis that ambient UV radiation protects against noncutaneous cancers via vitamin D synthesis, instead showing a modest positive association with overall cancer risk.
Limits
Exposure was modeled from geographic residence rather than direct personal dosimeters, time spent outdoors, or sun protection habits. The cohorts consisted entirely of US health professionals, limiting generalizability to broader demographic and occupational populations.