Photodynamic therapy for cutaneous squamous cell carcinoma in situ: Impact of anatomic location, tumor diameter, and incubation time on effectiveness.

Abstract

Photodynamic therapy (PDT) has been reported as a treatment for cutaneous squamous cell carcinoma in situ (SCCis), but only limited data are available on the effectiveness of PDT with aminolevulinic acid (ALA-PDT). To review the outcomes of SCCis treated with ALA-PDT and examine factors associated with response. A 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 reviews. On completion of PDT the initial complete response rate was 77.9% and was not associated with the number of PDT treatments. On multivariate analysis factors associated with response were location on the face, tumor diameter <2 cm, 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. This was a retrospective study performed at a single institution without systematic follow-up. ALA-PDT may be an effective treatment for selected cases of SCCis. Effectiveness is impacted by anatomic location, tumor diameter, and ALA incubation time.