The effect of phototherapy on progression to tumors in patients with patch and plaque stage of mycosis fungoides

Background: Phototherapy has been a mainstay in the treatment of mycosis fungoides (MF). However, the recent findings of UV-induced p53 mutations in advanced MF suggest that phototherapy may contribute to disease progression. Objective: The objective of this study was to evaluate the effect of phototherapy on the time to tumor progression and overall survival in MF. Materials and methods: Retrospective analysis of patients seen at the University of Pittsburgh Cutaneous Lymphoma Clinic from 1979 to 2016. Results: A total of 345 patients with MF were identified. 258 (74.8%) were diagnosed at stage IA or IB. 43 out of the 258 (16.6%) progressed to tumor stage. Before tumor development, 30 out of the 43 (69.8%) patients received phototherapy, and 13 (30.2%) did not. Patients who received phototherapy had a longer median time to tumor progression than those who did not: 3.5 years (interquartile range = 1.9-5.7) versus 1.2 years (0.2-2.3) (p = .001). Patients who received phototherapy also survived longer: 6.9 years (interquartile range = 4.3-9.5) versus 3.8 years (3.0-4.5) (p = .014). Limitations: Limited information on specific phototherapy start dates, durations, and treatment protocols. Conclusions: The therapeutic effects of phototherapy, with longer times to tumor progression and increased overall survival, appear to outweigh its potential adverse effects.