A retrospective review of pain control by a two-step irradiance schedule during topical ALA-photodynamic therapy of non-melanoma skin cancer

Background and Objective Photodynamic therapy (PDT) with topical δ-aminolevulinic acid (ALA) of non-melanoma skin cancers is often associated with treatment-limiting pain. A previous study on basal cell carcinomas (BCCs) at Roswell Park Cancer Institute evaluated a two-step irradiance scheme as a means of minimizing pain, preserving outcomes, and limiting treatment time. We used an initial low irradiance until 90% of the protoporphyrin IX was photobleached, followed by a high irradiance interval until the prescribed fluence was delivered. Success of this pilot investigation motivated integration of the protocol into routine practice. Here, we present a retrospective review of recent clinical experience in a broad patient population. Study Design/Materials and Methods This was a retrospective review of an existing dermatology database. Fourteen caucasion patients - nine men and five women, ages 18-80, with a total of 51 superficial and 73 nodular BCCs, and three Bowen's disease lesions - were included. ALA was applied to each lesion for approximately 4 hours. Lesions received an initial irradiance of 30-50 mW/cm² for 20 J/cm², followed by 150 mW/cm² for a total fluence of 200-300 J/cm². Pain was assessed using a visual analog scale (VAS). Clinical outcome was determined at 6-12 months. Results Median VAS scores were 1.0 for both irradiances. Five of 127 lesions required pain control with 1% xylocaine. Pain was strongly influenced by lesion location but not by lesion type, number, or size. Complete responses were achieved in 84.1% of BCCs, which compares favorably with reported results for single ALA-PDT treatments. Two of three Bowen's disease lesions showed a complete response. Complete responses for nodular BCCs were 37%, which are also within the range of reported outcomes. Conclusions A two-step irradiance protocol in ALA-PDT effectively minimizes pain, maintains excellent clinical outcomes in superficial lesions, and adds minimal treatment time.