Introduction: Topical photodynamic therapy (PDT) is a popular treatment for many non-melanoma skin cancers including actinic keratosis, Bowen’s disease, and some basal cell carcinomas. A chief complaint among patients is the pain that sometimes accompanies the procedure. This has led to a surge of interest in continuous, low-fluence rate PDT which is thought to be less painful. There is myriad evidence in the literature to suggest that natural sunlight can be an effective photo-activator of PpIX, the cytotoxic intermediate. However, there is some concern among the dermatological community regarding the degree to which this method of light delivery may be controlled. It is in this vein that we seek to compare the efficacy of natural sunlight with artificial light.
Purpose: The present study compares three low-fluence rate light sources in normal mouse skin, combined with ALA-PDT. The light sources of interest are natural sunlight, a 415 nm LED bulb, and a broad spectrum, white light, horticultural bulb.
Methods: A PpIX weighted fluence of 20 J/cm^2 was given to each light group, delivered over ~ 2 hours. Acute indicators of PDT efficacy were assayed via PpIX dosimetry, interrogation of Stat3 crosslinking, and analysis of epidermal keratinocytes for morphological changes.
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