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13 July 2009 Photodynamic therapy for difficult-to-treat basal cell carcinomas: Do poorly responding BCCs lack accumulation of protoporphyrin IX after ALA/MAL application?
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Proceedings Volume 7380, Photodynamic Therapy: Back to the Future; 73805K (2009) https://doi.org/10.1117/12.822981
Event: 12th World Congress of the International Photodynamic Association, 2009, Seattle, Washington, United States
Abstract
Photodynamic therapy (PDT) using topical application of aminolevulinic acid (ALA) and methylaminolevulinate (MAL) has become a popular therapeutic method for the treatment of non-melanoma skin cancers such as basal cell carcinomas (BCCs); however, the treatment response varies. An important question is if BCCs which respond poorly to PDT lack accumulation of protoporhyrin IX (PpIX) after ALA/MAL application. In connection to PDT, fluorescence diagnostics (FD) can be performed to detect PpIX within human skin. We investigated fluorescence images from 22 patients with 35 BCCs. They were evaluated with respect to the fluorescence contrast based on image analysis, which was considered to be a tool to non-invasively measure the PpIX-concentration. As expected the fluorescence contrast between tumor and normal skin was elevated after MAL-application; although no correlation between low fluorescence contrast and lack of treatment response could be observed. In a former study, we have also investigated the transdermal penetration of ALA and MAL in 27 BCCs in vivo using a microdialysis technique. In 15 of 16 BCCs in which the microdialysis catheter was located superficially (i.e. at a depth of less than 1 mm), therapeutic drug concentrations were detected;.however, in the 11 lesions with a deeper catheter location (below 1 mm) drug concentrations above the detection limit of the system were only obtained in 6 lesions (p=0.026). No difference between the transdermal penetration of MAL and ALA could be seen. Conclusions: Lack of PpIX fluorescence cannot entirely explain why some BCCs don't respond to PDT, but inadecuate concentrations within the full thickness of the tumor may play a role as microdialysis has shown.
© (2009) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Carin Sandberg, John Paoli, Christina B. Halldin, Martin Gillstedt, Olle Larkö, Ann-Marie Wennberg, and Marica B. Ericson "Photodynamic therapy for difficult-to-treat basal cell carcinomas: Do poorly responding BCCs lack accumulation of protoporphyrin IX after ALA/MAL application?", Proc. SPIE 7380, Photodynamic Therapy: Back to the Future, 73805K (13 July 2009); https://doi.org/10.1117/12.822981
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