BACKGROUND: Squamous cell carcinoma in situ (isSCC) is an early-stage cutaneous malignancy that requires effective treatment to prevent progression to invasive SCC. Aminolevulinic acid photodynamic therapy (ALA-PDT) is a noninvasive treatment that selectively targets neoplastic cells. This study evaluated the effectiveness, safety, and tolerability of ALA-PDT for the treatment of patients with facial isSCC. METHODS: In this single-center, investigator-initiated, open-label study (NCT06159842), adult patients with biopsy-confirmed facial isSCC received 2 treatments with 20% ALA and blue light exposure, administered 28 days (± 3 days) apart. Lesions were excised for histopathological assessment 8 weeks after the second treatment. The primary endpoint was complete histological clearance at the end of treatment (EOT). Secondary outcomes included clinical clearance and tolerability. RESULTS: A total of 32 patients were enrolled in this study, of whom 30 completed the study. All patients achieved complete histological clearance at EOT. Clinical clearance was observed in all patients prior to excision, with 40% achieving clearance by day 49 and the remainder by day 69. Local skin reactions, including erythema and flaking, were mild and resolved over time. Only 1 patient experienced temporary hyperpigmentation. Pain scores remained low (mean, 2.71/10). Two patients reported adverse events considered unrelated to treatment. CONCLUSIONS: ALA-PDT achieved 100% complete histological and clinical clearance with minimal adverse effects, demonstrating its potential as a safe, effective, and cosmetically favorable alternative to surgical excision for the treatment of facial isSCC. Further studies are needed to assess long-term recurrence rates and broader applications.
Nestor et al. (2026) studied this question.