The following is a summary of “Incidence and profile of skin cancers in patients following ultraviolet phototherapy without psoralens: A retrospective cohort study,” published in the April 2024 issue of Dermatology by Wang, et al.

Psoralen + ultraviolet-A (PUVA) therapy has been linked to photocarcinogenesis, raising concerns about the carcinogenic risk associated with other forms of ultraviolet phototherapy. However, the extent of this risk remains uncertain. For a study, researchers sought to assess whether phototherapy without psoralens increases the risk of skin cancer.

They conducted a retrospective cohort study involving patients treated at a phototherapy center affiliated with a teaching hospital between 1977 and 2018. Skin cancer diagnoses were validated against pathology reports. Age-standardized incidence rates (ASIRs) of skin cancer were analyzed based on gender, skin phototype, diagnosis, type of ultraviolet modality, and anatomical site. These rates were compared to provincial population incidence rates from 2003.

A total of 3,506 patients treated with broadband-ultraviolet-B, narrowband-UVB, and/or combined UVAB were included, with a mean follow-up duration of 7.3 years. Most patients had psoriasis (60.9%) or eczema (26.4%). The median number of treatments administered was 43 (range: 1-3598). Over the study period, 170 skin cancers were diagnosed in 79 patients, including 17 melanomas, 33 squamous cell carcinomas, and 120 basal cell carcinomas. The patient-based and tumor-based ASIRs of skin cancer were 149 (95% CI: 112-187) and 264 (95% CI: 219-309) per 100,000 person-years, respectively. No significant differences were observed in tumor-based ASIRs for melanoma, squamous cell carcinoma, or basal cell carcinoma compared to the general population, regardless of whether patients had psoriasis or eczema or received immunosuppressants. Additionally, no cumulative dose-response correlation was observed between UVB exposure and skin cancer risk.

The findings suggested that phototherapy without psoralens is not associated with an increased risk of melanoma or keratinocyte cancer.

Reference: jaad.org/article/S0190-9622(23)03270-X/abstract