P53 IMMUNOREACTIVITY IN CUTANEOUS PUVA TUMORS IS SIMILAR TO THAT IN OTHER NONMELANOMA SKIN NEOPLASMS

Expression of the p53 tumor suppressor gene product was determined in keratoses and skin cancers associated with psoralen photochemotherapy (PUVA). An immunocytochemical study was employed using CM-1 (polyclona l) and Do-1 (monoclonal) antibodies to human wild-type p53. Thirty-two cutaneous lesions and 20 perilesional PUVA-irradiated skin biopsies w ere examined from 7 patients, all of whom had received more than 200 P UVA treatments and/or a cumulative UVA dose of greater than 1000J/cm2 as treatment for widespread plaque psoriasis. p53 immunoreactivity was seen in 7 of 15 squamous cell carcinomas (46.7%), 5 of 8 dysplastic k eratoses (62.5%) and in no basal cell carcinomas or benign keratoses. The overall prevalence of p53 immunoreactivity in 46.2% of malignant o r dysplastic PUVA-associated skin tumors is similar to that previously found by our group in comparable skin tumors from the general populat ion. Most patients with lesions showing positive p53 immunoreactivity had, however, been exposed to additional risk factors before receiving PUVA therapy. p53 gene sequencing of PUVA-associated non-melanoma ski n cancer (NMSC) may clarify whether p53 mutation contributes to the de velopment of these tumors and whether this relates to PUVA therapy or prior carcinogen exposure.