Background: Previous large studies have shown that patients with cutaneous T-cell lymphoma are at increased risk for basal cell carcinoma and squamous cell carcinoma, and anecdotal case reports have suggested an association with malignant melanoma. It has been postulated that the exposure of cutaneous structures to potentially carcinogenic therapies, such as ionizing radiation or alkylating agents, might be causally associated with the development of these second cutaneous malignancies, but, to date, no study has directly addressed this issue. The purpose of this study was to evaluate the occurrence of second cutaneous malignancies in a group of patients with cutaneous T-cell lymphoma treated with total skin electron beam therapy and to examine the additional effects of oral psoralen with UV-A phototherapy, topical mechlorethamine hydrochloride therapy, and further radiation therapy. One hundred sixty-four patients with cutaneous T-cell lymphoma who had received total skin electron beam therapy between 1974 and 1990 were identified, and information was abstracted from their records.
Results: Six patients developed malignant melanoma 12 to 95 months after total skin electron beam therapy. Of the six patients, three had received oral psoralen with UV-A as additional therapy and two had received topical mechlorethamine. None had received additional radiation therapy. Twenty-four patients developed more than 37 basal cell carcinomas and 34 squamous cell carcinomas from 11 months to more than 10 years after total skin electron beam therapy. Of the 24 patients, 15 had received oral psoralen with UV-A and 12 had received mechlorethamine as additional therapy. Additional radiation therapy had been administered to nine patients. During a median follow-up of 6 years, no patients died of any second cutaneous malignancy.
Conclusion: We found a high rate of both melanoma and nonmelanoma skin cancer. The additional use of mechlorethamine or oral psoralen plus UV-A, but not radiation, was significantly associated with the development of basal cell carcinoma and squamous cell carcinoma, but not malignant melanoma.