Mutagen sensitivity in common cutaneous malignant melanoma and dysplastic naevus syndrome

Sunlight (ultraviolet radiation) has been identified as the major environme ntal risk factor for the development of cutaneous malignant melanoma and dy splastic naevi. This is, however, not sufficient to explain all melanoma ca ses. In recent years much emphasis has been given to genetic susceptibility to melanoma. A biomarker of susceptibility to environmentally related canc er is mutagen sensitivity. This is measured as the number of chromatid brea ks in lymphocytes which are exposed to bleomycin in the G(2) phase of the c ell cycle. It has been described that patients with common melanoma show an increased mutagen sensitivity compared with controls. In the present study mutagen sensitivity was measured in 10 dysplastic naevus syndrome patients and compared with that in 11 patients with common melanoma. We found simil ar results for common melanoma patients as have been reported earlier: a re latively high mean breaks per cell value (0.93 +/- 0.31). In contrast, mela noma patients with dysplastic naevi showed a significantly (P<0.01) lower m utagen sensitivity value (0.46 +/- 0.34). This phenomenon was even more pro nounced when only hereditary dysplastic naevi patients (one or more family members with dysplastic naevi) were considered (n=5; 0.24 +/- 0.05). These results suggest a difference in the initiation of the carcinogenic process in melanoma with a dysplastic naevus as a precursor and melanoma without dy splastic naevi. (C) 1999 Lippincott Williams & Wilkins.