Risk of skin cancers in mycosis fungoides patients receiving PUVA therapy: A real-life experience from a single tertiary center.

Background: Mycosis fungoides (MF) is the most common cutaneous T-cell lymphoma. Skin-directed therapies, including phototherapy, are the first-line treatment modalities. Psoralen plus ultraviolet A light photochemotherapy (PUVA) is quite effective in controlling the disease; however, long-term adverse effects, particularly carcinogenesis, are the cons of this treatment.

Objective: There are various studies on the negative impact of PUVA on skin cancer in patients with autoimmune skin diseases. The data on the long-term effects of phototherapy on MF patients are scarce.

Methods: All MF cases that received PUVA alone or combined with other treatments at a single tertiary center were analyzed. This study compared the development of non-melanoma skin cancers, melanoma, and solid organ tumors in MF patients with at least 5-year follow-up data with age- and sex-matched controls.

Results: A total of 104 patients were included in the study. Ninety-two malignancies were detected in 16 (15.4%) patients, and six developed multiple malignancies. Skin cancers consisted of 56 basal cell carcinomas, 16 Bowen's disease, four squamous cell carcinomas, three melanomas, two basosquamous cell carcinomas, one Kaposi sarcoma, and one keratoacanthoma were found in nine (8.7%) patients. Eight patients developed three solid cancers and six lymphomas. The risk of developing skin cancer was associated with the total number of PUVA sessions (<250 vs ≥250 sessions; hazard ratio (HR) 4.44, 95% confidence interval (CI) 1.033-19.068; p = .045). 9 (13.2%) of 68 patients who had follow-ups for at least 5 years developed skin cancer. Compared to an age- and sex-matched cohort, the prevalence of new skin cancer was considerably greater (p = .009).

Conclusions: Patients with MF are predisposed to develop secondary malignancies, and continual exposure to PUVA may potentiate this risk. Annual digital dermoscopic follow-up in MF patients treated with UVA is advised for early diagnosis and treatment of secondary cutaneous malignancies.