The role of DNA repair capacity in melanoma skin cancer risk in a population chronically exposed to high levels of sunlight.

Puerto Rican residents are exposed to some of the highest levels of environmental ultraviolet radiation in the world; paradoxically, the melanoma incidence in Puerto Rico is lower than that of the US mainland. The overall objective of this case-control pilot study was to test the hypotheses that (1) persons with melanoma have a significantly lower DNA repair capacity (DRC) in relation to controls matched by age, (2) decline in DRC is associated with vertical depth of melanoma invasion, and (3) DRC is associated with anatomical tumor location. Controls (n  =  124) were examined by dermatologists; cases (n  =  62) were histopathologically confirmed. The mean DRC ± 1 SE of controls was 6.46% ± 0.3. Melanoma patients (n  =  62) had a mean decrease in DRC of 3% (6.25% ± 0.5), which was not statistically different from controls (P  =  0.697). No significant differences in DRC were evident in participants with either in situ or malignant melanoma tumors; neither were such differences evident when evaluating anatomical location of tumors (ie, non-sun-exposed versus sun-exposed). DRC generally declined in participants with increased depth of melanoma tumor penetration when compared with controls and those with small in situ tumors. These findings should be examined in a larger-scale population study that includes participants with more advanced metastatic melanoma.