Solar Radiation Damage and the Induction of Skin Cancer.

Abstract

The very first international meeting on photobiology was held in Lausanne in 1928. To celebrate the 50th anniversary, a special meeting, over and above the usual 4 yearly congresses, was held once again in Lausanne. One might note in passing that a meeting on skin cancer, a Celtic disease, was particularly appropriate in Lausanne as the local museums show that this whole region is particularly rich in archaeological remains of the 'first' Celtic settlements.The international organizers, on behalf of the Association Internationale de Photobiologie (AIP), were Drs Dick Setlow, Rex Tyrell and Fred Urbach. The local organizers for the Swiss Institute of Experimental Cancer Research, in whose premises the meeting was held, included Drs Delacretaz, Odartchenko, Modak and the indefatigable Edgar Frenk, who was in charge of stage management. The local arrangements were excellent and the meeting very hard work, though enjoyable. The Swiss venue was naturally superb and the social side well organized.Most delegates were from either the U.S.A. or Western Europe, but some were from Australia, Brazil, India, Israel, Japan and South Africa. The personnel at the 1978 meeting refiects the changes in medicine since 1928. Instead of a predominantly clinical attendance as 50 years ago, the 100 or so delegates included biochemists, biologists, biophysicists, epidemiologists, experimental pathologists, geneticists, immunologists, meteorologists, microbiologists, molecular biologists, statisticians, and only a small clutch of clinical dermatologists, those with a specific interest in sunlight and the skin. Another difference in the 50 years was that the 1928 delegates optimistically considered the benefits of sunlight, whereas the 1978 meeting's title implies pessimism.The purpose of the 1978 Workshop-meeting was (a) to summarize the state of knowledge on sun exposure and skin cancer, at epidemiological, clinical, cellular and molecular levels; (b) to attempt estimates of rates of increase of incidence, and where possible to assess dose-response relationships, for both melanoma and non-melanoma cancers and (c) to make recommendations for the collection of data and the design of new experiments.The first session, chaired by Caldas (Brazil), AIP President, dealt with solar UVR damage and molecular changes to nucleoprotein, micro-organisms and mammalian cells in vitro. Tyrell (Brazil) showed that the intensively studied effects of 254 nm UVR may also be elicited with the longer wavelengths around 300 nm in terrestrial sunlight, though the action of broad band UVR is complicated by the different, sometimes opposite, effects of the constituent wavelengths. Peak (South Africa) then spoke on DNA transformation in B. subtilis and its mutation from 365 nm UVR and showed that this operated by a molecular pathway different to that induced by 254 nm. Helene (France) used model systems of nucleo-protein to demonstrate DNA changes from tryptophan photosensitization induced by 290 nm and longer wavelengths. Such may have more relevance for the compl...