Sun exposure, pigmentary traits, and risk of cutaneous malignant melanoma: a case-control study in a Mediterranean population.

The main objective of this study was to assess the influence of sun exposure and pigmentary traits on the risk of cutaneous malignant melanoma (CMM) in a Mediterranean population (Andalusia, southern Spain). Cases and controls were selected from 1988 to 1993. The study population included 105 incident cases with non-familial CMM (ICD-9 code 172) and 138 controls aged 20 to 79 years. Data were collected by personal interview, and melanocytic nevi were counted over the entire body surface. Crude, and multiple-risk factor adjusted, odds ratios (OR) and their 95 percent confidence intervals (CI) were computed. After adjustment, the major constitutional risk factor was skin type I-II (OR = 29.8, CI = 8.9-100) compared with skin type V. Statistically significant and positive trends were observed between the risk of CMM and occupational sun exposure of the skin (P = 0.003), recreational exposure (P < 0.001), and cumulative lifetime sun exposure (P < 0.001). Several characteristics related to sun exposure during summer increased the CMM risk, e.g., episodes of blistering sunburns and the number of sunbaths in childhood. Use of sunscreens and spending summer holidays in places other than beach were associated with a lower risk of CMM. Regarding pigmentary traits, CMM significantly occurred with more frequency in individuals with a high degree of freckling and quoted numbers of melanocytic nevi. In conclusion, the results support sun exposure and pigmentary traits (skin type, melanocytic nevi, and freckles) as main risk factors for CMM in this population.