I read with interest the first part of the European guidelines for photodynamic therapy (PDT). I am sure that putting up guidelines are necessary to improve the quality of outcome and as the authors mention in their introduction it should promote safe and effective practice. Therefore, I was astonished about the point concerning PDT and nodular basal cell carcinoma (BCC). The authors take reference to different publications with all pros and cons. They underline in one statement the better outcome of scars in patients treated by PDT for nBCC and they relativise high recurrence rate in another study because no debulking was performed before PDT. Finally, they conclude that PDT can be used for thin low-risk BCC. Already for an article of this value this definition is very relative because nobody knows what means thin in reality. Furthermore, the authors do not insist explicit on the point that PDT should not be used in high-risk BCC or nBCC in high-risk localization. This seems to me unfortunately a lack of this excellent publication.
We have shown in a study in 2012 that BCC recurrence after PDT therapy treated finally by Mohs surgery shows an upgrading in histologic aggressivity of the tumour. We have studied nodular and infiltrative BCC treated by PDT which recurred and examined in 16 cases of BCC the outcome measures concerning the histologic subtype before and after PDT. Recurrent BCCs of 62.5% displayed a transition from non-aggressive to an aggressive subtype. One major point which complicated surgery importantly was the fact that the tumour expansion was limited to the reticular dermis without showing any attachment to the epidermis. This makes this cases extremely challenging for any subsequent treatment after recurrence because clinically they are difficult to delimitate. Therefore, only Mohs surgery can resolve this delicate situation, but in these cases it is often associated with multiple surgical passes.
With the increase of incidence of non-melanoma skin cancer taking charge of patients with actinic skin damage will be challenging for the dermatologist and the healthcare system. Some publications are warning for major implications for future health care services. Therefore, dermatologists are longing for simple solutions for nodular or more aggressive BCC. But PDT cannot and should not be one of these solutions as might be suggested in this guidelines.
We raised concern whether PDT may select more aggressive tumour cells or may just traduce a natural course of tumour recurrence as we see with other treatment modalities. In any way there should be a clear consensus today that PDT treatment should only be applied to superficial BCC which have been biopsied before. Treatment of nodular or more aggressive BCC with PDT in high-risk area is obsolete. In case of recurrence after PDT treatment, surgery is always more devastating and more expensive because of the increased aggressivity as well the poor clinical delimitation of this tumours.
I think this point should have been added in your guidelines.