Cumulative sunlight exposure and the risk of developing skin cancer in Florida

Epidemiologic evidence suggests that the risk of developing skin cancer is higher in certain geographic regions where sunlight is excessive. Even in such high risk regions, two distinct populations of long-term residents exist: people with, and people without skin cancer. We have compared the quantitative lifetime sunlight exposure between 11 nonmelanoma skin cancer patients who have lived in South Florida for 23.7 +/- 5.1 years and 9 age-matched normal, healthy individuals who have lived in South Florida for 23.4 +/- 4.1 years. An estimation of personal cumulative sunlight exposure was determined for each subject from data collected through detailed interviews. We found that there was no detectable, significant quantitative difference in cumulative sunlight exposure during life between these two groups. Because these individuals had previously been phenotyped for the effects of ultraviolet-B (UVB) radiation on induction of contact hypersensitivity, our results suggest that UVB-susceptibility may be a better indicator of skin cancer risk than cumulative lifetime sunlight exposure. Thus, although there is little doubt that sunlight exposure is an important factor in the development of skin cancer, our results emphasize the importance of host genetic factors in the pathogenesis of this disease.