[Cutaneous senescence and carcinogenesis].

A variety of clinical, topographical, histological, epidemiological and geographical arguments attribute to the effects of solar radiation and to ultraviolet rays (UV) in particular, a decisive role in the processes of cutaneous carcinogenesis. This carcinogenicity is part of a series of chronic changes affecting the integument which constitute heliodermatitis or photosenescence. The effects of UV are cumulative. DNA is the main target of UV rays. Man possesses several DNA repair systems. The hereditary malfunction of part of these systems result in xeroderma pigmentosum, which constitutes a pathological model of photocarcinogenesis. Intrinsic skin ageing (non-photodependent) appears to promote this process of photocarcinogenicity by several mechanisms: summation of DNA changes, progressive deterioration of repair systems, dermal-epidermal atrophy, melanocytic changes, immuno-surveillance deficit.