Photodynamic therapy for cancers of solid organs

Photodynamic therapy (PDT) is the local destruction of tissue with light after prior administration of a photosensitising drug in the presence of oxygen. Most current applications are for cancers of the skin or hollow organs. The paper describes the new approach of interstitial PDT (iPDT) for image guided treatment of cancers of internal, solid organs. The main attractions of PDT are that connective tissues like collagen are largely unaffected, so the mechanical integrity of organs is preserved better than after other local treatments like heat and that there is no cumulative toxicity so, unlike radiotherapy, treatment can be repeated at the same site, if necessary. Further, as in most cases the therapeutic light can be delivered down fibres that are positioned directly in internal organs through needles that are inserted through the skin using various forms of image guidance, no open surgery is necessary, so recovery is faster. v Using PDT with light delivered via needles through the skin is an exciting new approach to treating a range of localised and well defined cancers in organs deep within the body. Preliminary results in the pancreas, prostate and neck are most encouraging, but larger scale studies are now required with further refinements in the technique, especially for optimising the light dosimetry. PDT has the potential to find an important role in cancer therapy, which is complementary to that of conventional treatments such as surgery and radiotherapy.