Epidermal urocanic acid concentration and photoisomerization reactivity inpatients with cutaneous malignant melanoma or basal cell carcinoma

The relationship of epidermal urocanic acid concentration and photoisomeriz ation reactivity to human skin cancer was studied. Twelve cutaneous maligna nt melanoma patients, 10 basal cell carcinoma patients and 22 healthy match ed controls were enrolled in the study. A solar simulating ultraviolet irra diator was used for phototesting the minimal erythema dose, Using the Finn Chamher((R)) technique, urocanic acid was sampled from the healthy skin of the upper back, prior to and after exposure to suberythemal UV doses, The m ean values of total and tr rms-urocanic acid were higher in basal cell carc inoma patients than in controls, but this difference was not statistically significant, No corresponding phenomenon was evident in the case of cutaneo us malignant melanoma patients and their controls. Photoisomerization induc ed by irradiation with 1 mJ/cm(2) CIE (Commission Internationale de l'Eclai rage) was statistically significantly lower in cutaneous malignant melanoma patients than in controls (p = 0.04). A similar trend was seen in basal ce ll carcinoma patients vs. their controls, but the difference was not signif icant.