Photodynamic therapy for cholangiocarcinoma using low dose mTHPC (Foscan(®))

Photodynamic therapy (PDT) combined with stenting is an effective treatment modality for palliation of nonresectable cholangiocarcinoma (CC). A drawback of standard PDT using Photofrin(®) as photosensitizer is the long lasting skin photosensitivity of up to 3 months. The aim of this study was to show the outcome of PDT of CC, potential side effects and to determine the best drug light interval (DLI) using mTHPC (Foscan(®)) at a low dose.

13 patients with nonresectable CC were treated with stenting and PDT (3mg Foscan(®) per treatment, 0.032-0.063 mg/kg body weight, 652 nm, 50 J/cm). Fluorescence measurements were performed with a single bare fiber for 5/13 patients prior to PDT at the tumor site to determine the fluorescence contrast. For another 7/13 patients, long-term fluorescence-kinetics were measured on the oral mucosa to determine the time of maximal relative fluorescence intensity.

The results so far indicate a median survival time of 13 months. Side effects such as perforations or skin phototoxicity could not be observed. Foscan(®) fluorescence within the tumor site was clearly detectable but a significant fluorescence contrast of tumor to adjacent healthy tissue could not be found. The fluorescence kinetics measured in the oral mucosa showed a maximum at 3.85 days (median) after drug administration.

Combined stenting and PDT performed with a low Foscan(®) dose results in equal and potentially longer survival times compared to standard Photofrin(®) PDT, while lowering the risk of side effects strongly. Thus it may improve the quality of life.