Photocarcinogenic Risk Associated With Narrowband UV-B Phototherapy: An Epidemiologic Study in a Tertiary Care Hospital

Incidence and profile of skin cancers in patients following ultraviolet phototherapy without psoralens: A retrospective cohort study

BACKGROUND

Psoralen + ultraviolet-A (PUVA) is associated with photocarcinogenesis. However, carcinogenic risk with other ultraviolet phototherapies remains unclear.

OBJECTIVE

Evaluate whether phototherapy without psoralens increases skin cancer risk.

METHODS

Retrospective cohort study of patients treated at a teaching-hospital phototherapy center (1977-2018). Skin cancer records were validated against pathology reports. Age-standardized incidence rates (ASIRs) of skin cancer were evaluated for gender, skin phototype, diagnosis, ultraviolet modality, anatomical site; and compared to provincial population incidence rates (2003).

RESULTS

In total, 3506 patients treated with broadband-ultraviolet-B, narrowband-UVB and/or combined UVAB were assessed with a mean follow-up of 7.3 years. Majority of patients had psoriasis (60.9%) or eczema (26.4%). Median number of treatments was 43 (1-3598). Overall, 170 skin cancers (17 melanoma, 33 squamous cell carcinoma and 120 basal cell carcinoma) occurred in 79 patients. Patient-based and tumor-based ASIR of skin cancer was 149 (95% CI: 112-187)/100,000 and 264 (219-309)/100,000 person-years, respectively. There was no significant difference between tumor-based ASIRs for melanoma, squamous cell carcinoma, and basal cell carcinoma compared to the general population; or in phototherapy patients with-psoriasis or eczema; or immunosuppressants. No cumulative dose-response correlation between UVB and skin cancer was seen.

LIMITATIONS

Treatment and follow-up duration.

CONCLUSION

No increased risk of melanoma and keratinocyte cancer was found with phototherapy.

UVB phototherapy in the treatment of vitiligo: State of the art and clinical perspectives

Vitiligo is a chronic pigmentary skin disorder that results in white, hypopigmented macules and patches. It causes a considerable psychological and emotional burden on the affected individuals and their families. Several therapeutic options have been employed in vitiligo including topical and oral drugs, surgical techniques, and phototherapy which is considered the cornerstone treatment. Different wavelengths and modalities are available, but narrowband UVB (NB-UVB) is considered the safest and the most effective phototherapy alternative. NB-UVB acts on multiple steps in vitiligo pathogenesis, and it is capable of inducing stabilization and repigmentation of vitiligo lesions. Technological advances have led to the development of both new phototherapy devices and new medical and surgical therapeutic options that can be combined with phototherapy to achieve optimal results. There is no standard treatment, and individual patient and disease characteristics should be considered. We review the current evidence in what concerns UVB phototherapy for vitiligo treatment, including novel combination treatments that may help to provide the best care for these patients.

Distinguishing Myth from Fact: Photocarcinogenesis and Phototherapy

Ultraviolet (UV) radiation contributes to the development of skin cancer through direct and indirect DNA damage, production of reactive oxygen species, and local immunomodulation. The association between UV radiation and skin cancer has raised concern for the risk of carcinogenesis following phototherapy. The photocarcinogenic impact of psoralen and UVA radiation (PUVA) has been extensively studied, whereas limited safety studies exist for other phototherapy modalities, such as broadband and narrowband UVB and UVA1. Because of the as of yet unclear risk, patients who have undergone any type of phototherapy should be followed for age-appropriate skin cancer screening.