RISK-FACTORS FOR NONMELANOMATOUS SKIN-CANCER IN ALEXANDRIA, EGYPT

The role of constitutional and environmental factors on the risk of no n-melanomatous skin cancer was evaluated in a case-control study condu cted in 1992 in Alexandria, Egypt, on 136 incident histologically conf irmed (99 basal-cell and 37 squamous-cell) cases of non-melanomatous s kin cancer (NMSC) and 145 controls in hospital for a broad spectrum of acute non-sun-related dermatological conditions. In relation to skin colour, compared with brown-skinned subjects, the multivariate relativ e risks (RR) were 2.3 for olive-skinned subjects and 3.8 for fair/medi um-skinned subjects. Three cases and 29 controls were black (RR = 0.2) . The trend in risk with skin colour was significant. Likewise, compar ed with subjects with brown or hazel eyes, those with green or blue ey es had a RR of 3.1. In relation to acute sun reaction, compared with s ubjects reporting easy tanning, the RRs were 2.5 for subjects reportin g moderate tanning and 4.7 for those reporting easy burning. The risk of NMSC was higher for subjects reporting an outdoor occupation than f or those reporting an indoor occupation (RR = 7.7). A significant tren d in risk was observed with degree of sun exposure: compared with subj ects reporting light sun exposure, the RR was 3.0 for those reporting moderate exposure, and 6.1 for those reporting heavy sun exposure. The re was an indication of a relationship between clothing pattern and sk in-cancer risk: compared with subjects reporting frequent use of tradi tional Egyptian clothes, the RR for dressing in short clothes was 1.8. The presence of sings of photodamage was also associated with NMSC (R R = 3.7). Exposure to arsenic was reported by 10 cases and 1 control ( RR = 9.5). A positive interaction between sun exposure and skin colour was observed, and the RR rose to 14.2 for medium- or fair-skinned sub jects with heavy exposure compared with brown- or black-skinned subjec ts with light or moderate sun exposure. In this Egyptian population, o ver 60% of NMSC could be attributed to sun exposure and approximately 45% to skin colour. (C) 1994 Wiley-Liss, Inc.