PDT: Advancing Therapy in Cholangiocarcinoma

PDT: Advancing Therapy in Cholangiocarcinoma

Cholangiocarcinoma is a relatively uncommon cancer, representing less than 5% of gastrointestinal (GI) malignancies. Unfortunately, it is also a relatively lethal cancer because advanced progression is already present before symptoms manifest in patients. Although cholangiocarcinoma tends to have a poor prognosis, there is some hope in the form of a new type of treatment called photodynamic therapy (PDT). 

PDT involves the administration of an intravenous photosensitizer, such as porfimer sodium, accompanied by the application of a specific wavelength of light to the affected area of the hepatobiliary ducts. The photosensitizer interacts with the light, causing a chemical reaction that produces free radicals that potentially kill the ductal cancer cells as well as decrease a portion of the obstruction caused by the cancer. PDT is not necessarily considered a first-line treatment and is usually reserved for patients with locally unresectable or recurrent cholangiocarcinoma.

Although there is a fair amount of clinical data on PDT in other types of diagnoses, including lung cancer, there is not an overwhelming amount of research done in cholangiocarcinoma patients. Some small clinical trials have shown prolonged survival in patients receiving PDT compared with those who received biliary stenting alone. Ortner and colleagues showed that in a group of 19 patients with cholangiocarcinoma, the PDT with biliary stent group had a median survival time of 493 days compared with 98 days in the stenting-only group. An additional study by Zoepf and colleagues showed a similar benefit in median survival time in 32 patients treated with either PDT or biliary stenting (630 days vs 210 days, respectively). These studies do provide some insight into the potential benefit of PDT; however, the number of patients studied is relatively small at this time.

Of course, no treatment is without its risks. The major side effects of PDT include photosensitivity, cholangitis, cholecystitis, and liver abscesses. The infectious complications have been successfully treated with antibiotics and have occurred in the control patients in the above studies as well. Patients treated with PDT are immediately at increased risk for sunburn and should avoid overexposure to sunlight for up to 4 to 6 weeks after receiving treatment.    

Cholangiocarcinoma is clearly a deadly diagnosis with limited treatment options at the time of patient presentation. The clinical data investigating the utility of PDT in cholangiocarcinoma is accruing; however, more studies are needed in order to show a significant clinical benefit. Additional clinical studies will also prove helpful in extending a unique treatment such as PDT to a more substantial proportion of patients with cholangiocarcinoma.

• What are your experiences with PDT in patients with cholangiocarcinoma?

• What challenges do you foresee with using PDT in patients with cholangiocarcinoma?