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.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.