A Prospective Study of Pain Control by a 2-Step Irradiance Schedule During Topical Photodynamic Therapy of Nonmelanoma Skin Cancer

BACKGROUND Topical photodynamic therapy (PDT) for selected nonmelanoma skin cancer using 5-aminolevulinic acid (ALA) or methyl aminolevulinate (MAL) has yielded high long-term complete response rates with very good cosmesis. Pain during light activation of the photosensitizer can be a serious adverse event. A 2-step irradiance protocol has previously been shown to minimize ALA-PDT pain. OBJECTIVE To determine the irradiance-dependent pain threshold for MAL-PDT, to adapt the 2-step protocol to a light-emitting diode (LED) light source, and assess clinical response. METHODS In this prospective study, 25 superficial basal cell carcinoma (sBCC) received an initial irradiance by laser at 40 or 50 mW/cm(2), or LED at 35 mW/cm(2) followed by an irradiance at 70 mW/cm(2) for a total of 75 J/cm(2). Pain levels were recorded for both irradiance steps. Efficacy was assessed at 6, 12, or 24 months. RESULTS Pain was mild in the 40/70 mW/cm(2) laser cohort. Three instances of irradiance-limiting pain occurred at 50/70 mW/cm(2). Pain was minimal in the 35/70 mW/cm(2) LED cohort. Clinical response rates were 80% in the 50/70 mW/cm(2) laser cohort and 90% in the 35/70 mW/cm(2) LED cohort. CONCLUSION Topical PDT can be effectively delivered to sBCC with minimal treatment-related pain by a 2-step irradiance protocol.