SKIN-CANCER IN A SUBTROPICAL AUSTRALIAN POPULATION - INCIDENCE AND LACK OF ASSOCIATION WITH OCCUPATION

Because it is not possible to monitor skin cancer accurately using rou tine methods, special surveys have been undertaken in Nambour, a typic al subtropical community in Queensland, Australia. Estimates of incide nce reported here are based on skin cancers medically treated between 1985 and 1992 and new cases diagnosed by dermatologists in two examina tion clinics in 1986 acid 1992. Among men and women aged 18-69 years i n 1986, age-adjusted incidence rates of basal cell carcinoma were 2,07 4 and 1,579 per 100,000 per year, respectively-the highest incidence r ates of a specific cancer ever reported. Squamous cell carcinoma occur red at half the rate of basal cell carcinoma among men and at about on e third the rate among women. Although as expected, fair skin, a histo ry of repeated sunburns, and nonmalignant solar skin damage diagnosed by dermatologists were strongly associated with both types of skin can cer, outdoor occupation was not. Significant self-selection was observ ed among outdoor workers, whereby people with fair or medium complexio ns and a tendency to sunburn were systematically underrepresented amon g those in long-term outdoor occupations although they accounted for m ore than 80 percent of the community study sample. The mitigating effe ct of this selection bias may partly explain the paradox of the lack o f quantitative evidence of a causal link between sun exposure and skin cancer in humans.