[Psoriasis and cancer].

This study reports the cancer incidence among 6910 individuals in Denmark discharged from hospital over the period 1977-1987 with a diagnosis of psoriasis. Patients were identified in the National Hospital Discharge Register and information on cases of cancer was obtained through the files of the Danish Cancer Registry. A 2,5-fold increased risk was observed for nonmelanoma skin cancer in men and women, with no preponderance of any specific histologic subtype of cancer. The incidence of non-cutaneous cancers at all sites combined was significantly increased in the study group, owing mainly to excesses of lung cancer in men (relative risk (RR) = 1.4) and women (RR = 1.6), of cancer of the larynx and pharynx in men (RR = 2.8 and 3.9), and of colon and kidney cancer in women (RR = 1.6 and 2.3). The effect of cigarette smoking on the risk for non-cutaneous cancer could not be assessed in this study; however, antipsoriatic treatment such as ionizing radiation and oral arsenicals must be considered as a possible cause, particularly in relation to colon cancer which has been observed in excess in two other studies of psoriatic patients, but also in relation to kidney and lung cancer.