The relative importance of risk factors in nonmelanoma carcinoma.

The relative importance of risk factors such as solar exposure, complexion, age, and the ability to tan were examined for their relationships to the development of basal and squamous cell carcinoma. Three samples were studied: patients with basal cell carcinoma (N = 366), patients with squamous cell carcinoma (N = 58), and control subjects (N = 294). The technique of logistic regression was used to estimate the relative risk of each type of carcinoma. Solar exposure was the most important risk factor for both basal and squamous cell carcinoma; however, the ability to tan was shown to be of special importance even at low levels of exposure. Given the same level of cumulative lifetime solar exposure, subjects over 60 years of age were shown to be at higher risk for nonmelanoma carcinoma than those at younger ages. Complexion was only shown to be significant for basal cell carcinoma.