Sensitivity to ultraviolet B is a risk factor for cutaneous melanoma in a Mediterranean population: results from an Italian case-control study

Abstract

Sun sensitivity is one of the predictors of melanoma risk, together with other individual characteristics such as skin and eye colour and number of naevi. However, it is unclear how best to measure sun sensitivity in order to quantify the individual risk of melanoma. In this case-control study, the relationship between minimal erythema dose (MED) and skin colour (both instrumentally assessed) was investigated, and their possible role as independent risk factors for melanoma in a Mediterranean population evaluated. In total, 143 patients with cutaneous melanoma and 102 controls were enrolled in the study. Skin colour was assessed using a Minolta CR-200 chromameter. For MED calculation, a fluorescent lamp (Philips TL 4W/12) was used as a source of ultraviolet B light. MED was defined as the lowest dose that produced an increase of 2.5 in the redness value, expressed by the parameter a* of the Commission Internationale d'Eclairage (CIE) L*a*b* colour space (Deltaa* = 2.5). A significant excess of risk was associated with increasing L* values of skin colour (P < 0.05; OR = 1.12; 95% CI 1.01-1.24) for each unit of change. Low MED values were also associated with an increasing risk of melanoma, with an excess of risk of 18% (OR = 1.18, 95% CI 1.04-1.35) for every 10 mJ/cm(2) of MED reduction. Compared with the highest MED values (> 97.7 mJ/cm(2)), subjects with MED values <or= 50 euro mJ/cm(2) or lower had a > 2-fold increased risk of melanoma (OR = 2.37, 95% CI 1.05-5.38). The effect of decreasing MED value as a melanoma risk factor persisted after adjustment for skin colour and atypical naevi in a multivariate model. In conclusion, both instrumentally assessed skin colour and MED are significant risk factors for malignant melanoma in a Mediterranean population. MED seems be an independent variable in establishing the subject's risk profile.