Photodynamic therapy of cholangiocarcinoma.

Photodynamic therapy (PDT) is a local photochemical tumor treatment that consists of a photosensitizing agent in combination with laser irradiation of a distinct wavelength. In some case reports and small non-randomized pilot studies, PDT has proved feasible in patients with hilar bile duct cancer. Those studies showed an astonishing long survival time of the treated patients. In the yet published two randomized controlled studies, PDT showed a significant extension of survival compared to sole bile duct stenting. A possible explanation for this improved survival is a suspected anti-tumor immunological effect induced by PDT. PDT reaches the same level of survival time as incomplete resection. The main complication is a high risk of severe bacterial cholangitis and liver abscesses requiring peri-interventional antibiotics. Skin phototoxicity, which at the beginning of PDT was the most dreaded potential complication, seems to play an ancillary role using mild light protection. As the available photosensitizers, mainly hematoporphyrin derivative (HPD), are not very effective in terms of depth of tumor necrosis, newer photosensitizers with light absorption in the near infrared spectrum and therefore deeper penetration depth are currently under investigation.