Risk of Skin Cancer with Phototherapy in Moderate-to-Severe Psoriasis: An Updated Systematic Review.

Phototherapy is a standard treatment for moderate-to-severe psoriasis. However, concern remains regarding the associated cutaneous carcinogenic risk. Our objective is to conduct a systematic review of skin cancer risk for psoriasis patients treated with phototherapy. To achieve our goal, we searched Cochrane, PubMed, and Embase databases. We aimed to evaluate existing literature (from July 1, 2010, to December 31, 2020) on phototherapy for all Fitzpatrick skin phototypes (FSP) which includes 71 articles, and eight articles being categorized in this review. Five studies did not report an increased skin cancer risk with narrowband-ultraviolet blue (UVB) and unspecified UVB for FSP II through VI, with one study not reporting FSP. Three studies did report an increased risk of skin cancer with narrowband-UVB and broadband-UVB for FSP I-VI, with one study also not specifying skin phototypes or UVB phototherapy type. Additionally, a study with psoralen and ultraviolet A with and without narrowband-UVB demonstrated an increased risk of skin cancer in phototypes III and IV. The most commonly reported secondary outcomes with phototherapy were actinic keratosis (123) and solar lentigines (10). Numerous patients were also on additional therapies including methotrexate, acitretin, and biologics. Study limitations include publication bias due to limited number of studies published on this topic in the last ten years along with heterogeneity in reporting. The relationship between phototherapy, psoriasis, and cutaneous oncogenic risk remains contradictory. While phototherapy for psoriasis is an efficacious therapy, further studies are needed to understand the cutaneous oncogenic risk based on FSP to help clinicals tailor treatment recommendations based on skin phototypes.