Comparison of the Treatment Outcomes of Photodynamic Therapy and Ingenol Mebutate in Bowen's Disease: A Retrospective Observational Study.

Background: Bowen's disease (BD) is treated by multiple treatment modalities.

Objective: To assess the effectiveness of photodynamic therapy (PDT) and ingenol mebutate (IMB) in treating BD and determine the factors affecting the treatment outcome.

Methods: Patients with histologically confirmed BD from January 1, 2006, to December 31, 2017, were identified from the database of CHA Bundang Medical Center. Those treated with PDT or IMB were included. Patient, tumor characteristics, and treatment response data were retrospectively collected from the database.

Results: Overall, 44 and 24 BD were treated with PDT and IMB, respectively. Mean time to the first follow-up visit was 1.2 (0.5~4) months. Mean follow-up duration was 7.6 (1~36) months. The mean number of treatment sessions for PDT is 2 sessions (1~5), while that of IMB was equally 1 session. The complete response rates at the first follow-up visit were 66.7% and 53.0% and recurrence rates were 10.3% and 15.3% for PDT and IMB, respectively. However, the treatment outcome and recurrence rate between both treatment modalities were not significantly different (=0.349 and =0.993, respectively). In factor analysis, the complete response rate significantly decreased with older patients in IMB (=0.012). Adverse events, occurred in 20.5% and 45.8% of patients treated with PDT and IMB, respectively.

Conclusion: PDT and IMB are effective noninvasive treatment modalities for BD. However, PDT is a safer treatment modality, considering its fewer adverse events. Particularly, with age being a factor that reduces IMB outcome, in older patients, PDT can be considered as preferred treatments over IMB.