a 5.7-year prospective study of 1380 patients treated for psoriasis with oral methoxsalen ( 8-methoxypsoralen ) and ultraviolet a photochemotherapy ( puva ) revealed that after adjustment for exposures to ionizing radiation and topical tar preparations , the risk that cutaneous squamous-cell carcinoma would develop at least 22 months after the first exposure to puva was 12.8 times higher in patients exposed to a high dose than in those exposed to a low dose ( 95 per cent confidence interval , 5.8 to 28.5 ) .
C0033860
psoriasis
C0025684
8-methoxypsoralen