RESUMEN
BACKGROUND: Photodynamic therapy (PDT) is an FDA approved treatment for actinic keratoses (AK's) although multiple off-label indi- cations are reported. Despite frequent use for AK's, no clear consensus exists regarding protocols for overall treatment parameters. METHODS: Retrospective chart review of 1,491 subjects who underwent PDT between 2007 and 2011 at a high volume laser surgery center. Demographic information, clinical history, treatment data, and subsequent diagnosis of skin cancers were recorded. An ex- ploratory subgroup analysis was performed for patients treated for AK and/or squamous cell carcinoma (SCC) that developed SCC or remained SCC-free one year after treatment. RESULTS: The most common indications for PDT were actinic keratoses (n=1404, 94.9%) then NMSC (n=45, 3.0%) The most common treatment site was the head and neck (n=1274, 86.1%). Blue light activation (405-420nm) was used more frequently than red light and visible light. (73.8% vs. 22.8% vs. 6.8%). The most commonly used photosensitizer was aminolevulinic acid (ALA) (98.6%, n=1456). Topical application (97.7% n=1437) of photosensitizer was used more frequently than intralesional administration (2.0%, n=29). 580 patients met subgroup analysis criteria. 66 developed SCC at treatment site (11%). Factors associated with developing SCC were older age, SCC history, Fitzpatrick skin-type 1, and sixty-minute or less incubation times (P less than 0.05 for all factors). The SCC subgroup had a unique distribution of treatment sites (P less than.001). No statistically significant differences were observed for gender or wavelength. CONCLUSION: There are differences in protocols based on indication and location of lesion. Blue light is preferable for superFIcial lesions and red light for deeper lesions. Intralesional delivery is used more commonly for NMSC. Extremities require longer incubation times. PDT may be more effective with younger patients and longer than sixty-minute incubation times. PDT chemoprevention is independent of light source used. J Drugs Dermatol. 2016;15(11):1420-1426..
