Surgical scar remodelling after photodynamic therapy using aminolaevulinic acid or its methylester: a retrospective, blinded study of patients with field cancerization.

ABSTRACT

BACKGROUND: Photodynamic therapy (PDT) is a nonsurgical alternative to conventional tumour excision for nonmelanoma skin cancers (NMSCs). OBJECTIVES: We evaluated whether patients with field cancerization (multiple NMSCs) treated with aminolaevulinic acid (ALA) or its methylester (MAL) for that indication had PDT-induced changes in surgical scars in the treatment field. METHODS: Six adult patients with multiple NMSCs and a total of 21 scars from previous excisions were studied in a retrospective blinded evaluation from clinical photographs of scar response to ALA/MAL-PDT. After a 3-h application of topical 20% ALA or 16·8% MAL under occlusion, each field was irradiated with 635-nm light-emitting diode light at the fluence of 200Jcm(-2) . Patients underwent one to three PDT sessions per field at ∼1month intervals, to fields that included scars on the back, thigh, arms and neck. Pre- and post-treatment digital photographs of scars were combined into 92 pairs that were independently and blindly evaluated by three board-certified dermatologists. This study was performed at our academic practice at the Massachusetts General Hospital. RESULTS: PDT produced a statistically significant improvement in scar appearance. The degree of improvement correlated with the number of treatment sessions (two or three treatments; P<0·05). Improvement after a single treatment was not statistically different from baseline ratings (P=0·99). CONCLUSIONS: Surgical scar remodelling and clinical improvement may be accomplished via ALA/MAL-PDT, but may require repeated treatment sessions. Larger, prospective studies are necessary to confirm the effectiveness of PDT for this indication.