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.
PDT is an effective method when treating multiple actinic keratoses (field cancerization). The major side effect is pain.
Our objectives were to investigate the pain-relieving effect of transcutaneous electrical nerve stimulation (TENS) and
peripheral nerve blocks during PDT of field cancerization (FC) of the face and scalp. Patients with field cancerization
were included in three studies. In the first study, we examined TENS with an application site on the adjacent dermatome
from the PDT area in order to allow the use of water spray during PDT for FC of the scalp and face. In the second study,
patients with FC in the facial area received unilateral supraorbital, infraorbital and/or mental nerve blocks. The non-anaesthetised
side of the treatment area served as control. In the third study, with similar methodology as in the second
study, occipital and supraorbital nerve blocks were combined for FC of the forehead and scalp. The results of the studies
strongly support the use of nerve blocks as pain relief during PDT. The use of TENS provided a limited pain reduction,
but TENS might be an alternative if the patient disapproves of the use of nerve blocks or is afraid of injections.
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