Photodynamic therapy for cutaneous squamous cell carcinoma in situ: impact of anatomic location, tumor diameter and incubation time on effectiveness
Background Photodynamic therapy (PDT) has been reported as a treatment for cutaneous squamous cell carcinoma in situ (SCCis) but there is limited data on the effectiveness of PDT with aminolevulinic acid (ALA-PDT). Objective To review the outcomes of SCCis treated with ALA-PDT and examine factors associated with response. Methods Retrospective review identified 58 patients with 68 primary SCCis lesions treated with ALA-PDT and blue light illumination. Patient demographics, lesion features, treatment details, clinical response, and subsequent recurrence were extracted from medical record review. Results Upon completion of PDT, the initial complete response rate was 77.9% and was not associated with the number of PDT treatments. On multivariate analysis, the factors associated with response were location on the face, tumor diameter <2 centimeters, and longer ALA incubation time. Lesions treated with a maximum incubation time of <3 hours had a 53.3% response compared with 84.9% for longer incubation. Subsequent recurrence of SCCis was noted in 7 of 53 cases (13.2%) at a median time of 11.7 months. Limitations This was a retrospective study performed at a single institution without systematic follow-up. Conclusions ALA-PDT may be an effective treatment for selected cases of SCCis. Effectiveness is impacted by anatomic location, tumor diameter, and ALA incubation time. This Dataset is Supplementary Data for the manuscript, "Photodynamic therapy for cutaneous squamous cell carcinoma in situ: impact of anatomic location, tumor diameter and incubation time on effectiveness." Authors: Nour Kibbi, MD, Yuemei Zhang, MD, MBA, David J. Leffell, MD, and Sean R. Christensen, MD, PhD Accepted for publication by Journal of the American Academy of Dermatology 2019 (JAAD-D-19-01312R1). Supplementary Figure 1. Response of SCCis according to number of PDT treatments. A, Initial complete response for all lesions and according to number of PDT treatments. B, Durable complete response at final follow-up for all lesions and according to number of PDT treatments. Supplementary Figure 2. Occlusion during PDT incubation period was significantly associated with incubation time. P value was calculated using the Spearman correlation. Supplementary Table. Factors associated with recurrence of SCCis after initial complete response.