A new study published in Photodermatology, Photoimmunology & Photomedicine it was shown that in Asian skin, narrowband ultraviolet B (NBUVB) phototherapy increases the risk of skin cancer.

Few research have been done on Asian patients compared to Caucasians on the risk of skin cancer associated with NBUVB. In order to ascertain the risk of skin cancer in Asian patients with psoriasis and vitiligo following NBUVB phototherapy, this study was carried out by Brian Chia and team.

All patients with psoriasis and vitiligo who received NBUVB (either 311nm wavelength through cabin phototherapy or 308nm wavelength using excimer lamp phototherapy) at the National Skin Center were included in a nine-year retrospective research. In order to conduct this study, researchers collected information on all skin cancer diagnoses and matched patient identifying numbers to the National Registry of Diseases Office database.
The key findings of this study were:

1. There were 3730 patients covered in all. 12 cases of skin cancer were identified throughout the investigation, of which 10 were basal cell carcinomas and 2 were squamous cell carcinomas.
2. In the study, no melanoma instances were found.
3. In patients with vitiligo and psoriasis who underwent phototherapy, the age-standardized incidence of skin cancer was 47.5 and 26.5, respectively, which is greater than the occurrence of skin cancers in the general population.
4. The cumulative (p=0.008), maximum (p=0.011), and prior systemic treatments (p=0.006) all linked favorably with the risk of skin cancer.
In conclusion, patients with psoriasis are more likely to develop skin cancer due to their higher cumulative and maximal phototherapy doses, systemic therapy use, and other risk factors. Despite the elevated risk, there are still few skin cancer cases overall, especially among vitiligo patients, and no cases of melanoma have been reported. This reassuring finding confirms that phototherapy is still a safe alternative for treating psoriasis and vitiligo.
Reference:
Chia, B. K. Y., Yew, Y. W., Zhao, X., Chong, W., & Thng, T. G. S. (2022). Incidence of skin malignancies in patients with vitiligo or psoriasis who received narrowband ultraviolet B phototherapy (308nm/311nm): a retrospective review of 3730 patients. In Photodermatology, Photoimmunology & Photomedicine. Wiley.https://doi.org/10.1111/phpp.12844