Non melanoma skin cancer of the scalp. On the etiology.

In order to evaluate the relative significance of previous grenz-ray treatment for human non melanoma skin carcinogenesis, the files were studied of all patients treated for non melanoma skin cancer of the scalp (n = 82, male/female ratio 1.1) at the Department of Dermatology, the Finsen Institute, from 1976 to 1985. Fourteen patients, with a male/female ratio of 3.7, were treated for squamous cell cancer (SCC). Sixty-five patients, with a male/female ratio of 0.9, were treated for basal cell cancer (BCC). Twelve patients (15%, 11 with BCCs, 1 SCC), of which eight with psoriasis, were previously treated with grenz rays on the scalp, and two of them had not been exposed to additional skin carcinogens. Comparably, malignant conversion in sebaceous and verrucous nevi accounted for 9 cases or 11%. Characteristically, scalp cancers associated with previous grenz-ray treatment were BCCs, the male/female ratio were less than 0.1 and two-thirds occurred in patients with multiple skin cancer. That grenz-ray related scalp cancers more often develop in females than in males was further confirmed by comparison to the sex distribution among patients treated on the scalp with grenz rays in the years 1950, 1960 and 1970 (p less than 0.01). (Accepted August 10, 1988.)