Effect of Methyl Aminolevulinate Photodynamic Therapy With and Without Ablative Fractional Laser Treatment in Patients With Microinvasive Squamous Cell Carcinoma: A Randomized Clinical Trial.

Importance: Surgical excision is the standard treatment for cutaneous squamous cell carcinoma (SCC). However, microinvasive SCC (Clark level II) is limited to the papillary dermis, and it should be differentiated from invasive SCC. Ablative fractional laser-primed photodynamic therapy (AFL-PDT) may have enhanced efficacy.

Objective: To compare 1 session of AFL-PDT with 2 sessions of conventional methyl aminolevulinate-PDT (MAL-PDT) for the treatment of microinvasive SCC.

Design, Setting, and Participants: A 2-armed, randomized, single-blind, comparative trial of 45 patients with histologically proven microinvasive SCC. Twenty-one patients were randomized to treatment with a single AFL-PDT session, and 24 patients were randomized to 2 MAL-PDT sessions with a 1-week interval between sessions using a computer-generated program. Standard pretreatment such as curettage was not performed prior to PDT owing to a tendency to bleed. The efficacy, recurrence rate, cosmetic outcomes, and safety were assessed 1 week, 3, 12, and 24 months after the last treatment.

Interventions: AFL was performed with an ablation depth of 550 µm to 600 µm, coagulation level of 1, treatment density of 22%, and a single pulse. Then, MAL cream was applied under occlusion for 3 hours and illuminated by using a red light-emitting diode light at 37 J/cm2. A second session of MAL-PDT was administered after 7 days.

Main Outcomes and Measures: The primary outcome measures were the lesion response at 3 and 12 months, and the recurrence rate 12 months after the last treatment.

Results: Twenty-one patients (6 men, 15 women) with a mean (SD) age of 76 (6) years were randomized to treatment with a single AFL-PDT session, and 24 patients (11 men, 13 women) with a mean (SD) age of 75 (6) years were randomized to 2 MAL-PDT sessions. The overall complete response rates 3 months after treatment were 84.2% with AFL-PDT and 52.4% with MAL-PDT (P = .03). These differences in efficacy remained significant at the 24-month follow-up. The recurrence rate was significantly lower with AFL-PDT (12.5%) than with MAL-PDT (63.6%) at 24 months (P = .006). AFL-PDT and MAL-PDT did not differ significantly with respect to the cosmetic outcomes, adverse events, or pain intensity.

Conclusions and Relevance: AFL-PDT can be used as an alternative treatment option for patients with microinvasive SCC who are not suitable for surgical treatment.

Trial Registration: clinicaltrials.gov Identifier: NCT02666534.