The persistent risk of genital tumors among men treated with psoralen plus ultraviolet A (PUVA) for psoriasis

Background. In the general population, squamous cell carcinomas (SCCs) of the male genitalia are rare. Ten years ago, we documented a significant dose-dependent increase in the risk of malignant genital neoplasms among men treated with psoralen plus ultraviolet A (PUVA). Since that time, fewer cohort patients have used PUVA, and genital protection among PUVA users is likely to be frequent. Objective: Our aim was to determine the incidence and risk factors for genital neoplasms since 1989 and risk factors for these neoplasms among patients treated with PUVA. Methods. We conducted a prospective cohort study of 892 men first treated with PUVA in 1975-1976. Results: Twenty-four men (2.7%) had 51 genital neoplasms, including 10 patients with a first tumor after May 1, 1989 (the ending date for our 1990 report). Since May 1, 1989, the incidence of invasive penile and scrotal SCCs was elevated 52.6-fold (95% confidence interval, 19.3-114.6) compared with that expected for the general white population. Multivariate models revealed the highest genital tumor risk among men with high-dose exposure to both PUVA and topical tar/ultraviolet B, with an incidence rate ratio of 4.5 (95% confidence interval, 1.3-16.1) compared with the low-dose exposure group. Conclusion: Although use of PUVA has decreased and genital shielding in our cohort has increased, the dose-dependent increase in the risk of genital tumors in men treated with PUVA has persisted. Particularly high risks occur among those with high-dose exposures to both PUVA and topical tar/ultraviolet B.