INTERSTITIAL PDT FOR PRIMARY AND METASTATIC TUMOUR

Photo courtesy of House of Laser

PDT is one of the interesting modalities in cancer treatment.The availability of several photosensitizers and lasers are opening new pathways in photodynamic medicine, leading to a new era in the future of medicine.
(It should be mentioned that PDT will not be an umbrella only in oncology but will cover some areas including infectious and other degenerative processes or diseases as well.)
A technique of interstitial PDT has been offered in conjunction with other modalities in cancer treatment,as shown in this picture.
Selective cancer cells death by apoptosis and necrosis has been proposed to a formation of lysate following cytotoxic process of cancer cells.
Secondly vascular shutdown is another way to the killing of cancer cells.
Positive immune response is another way leading to improvement of patient condition.(see: Immunologic aspect of PDT/Laser therapy,a review by Santoso Cornain,MD,D.Sc, a link in this blog)

PDT: AFTER 2X24 HOURS

Interstitial technique of PDT is used to debulk huge tumours.
The debulking process started hours after illumination by direct cytotoxic effect of PDT into tumour cells and by vascular shutdown
resulting in tumor apoptosis and necrosis.
In order to treat tumours thicker than 1 cm(limit of light penetration depth into the human tissue),the interstitial illumination technique was invented.
By this technique laser fibres with a light diffuser at the tip are implanted into the tumour tissue.
Laser fibres are feed-through needles,which can be placed under image guidance in the tumour(CT,MRI or US).
In large tumours,several fibres can be placed close to each other(12 cm apart) in order to illuminate the entire tumour volume.
Interstitial light delivery allows PDT to be used in the treatment of large,buried tumours and is particularly suitable for those whose surgery would involve extensive resection or for those who are unsuitable for surgery.
Due to the difficult and non precise light dosimetry in the tumout,interstitial PDT is mainly used with palliativeintention,as stated by Xu et al.
The pictures shown are PDT in large tumour of the neck,before (upper picture)and 2x24 hours (lower picture)after laser interstitial illumination.