Treating a rare form of liver cancer
Perihilar cholangiocarcinoma (PC) is a rare form of liver cancer that originates in the epithelial cells of the bile duct. The cancer is usually diagnosed at an advanced stage and carries a high risk for a poor outcome. Since both the bile ducts can be affected, surgical resection alone is not a treatment option.
A three step method is employed in the management of advanced PC, namely, a highly specialized form of radiation therapy (hyper-fractionated radiotherapy), chemotherapy, followed by a liver transplant. This method has been able to provide good clinical outcomes.
The type of radiation therapy given is called hyper-fractionated radiotherapy. This process involves the delivery of very small (1.5 gray per fraction) radiation treatments in two separate daily doses.
The second dose is given later in the day to allow the tissue to heal from the first radiation dose. The treatment is continued Monday through Friday, for three weeks (30 doses) as an outpatient procedure.
Standard radiation involves higher doses that could potentially scar adjacent tissue with more damage to the bile ducts necessary for liver transplant, and is hence not recommended.
Hyper-fractionated radiotherapy is gentler to the tissues. It is delivered by focusing the radiation beam on the tumor and reduce the intensity of radiation to the surrounding healthy tissues (intensity-modulated radiation therapy — IMRT).
IMRT uses multiple beams and creates angles to form a stronger focal point of radiation, sparing the surrounding normal tissues. Furthermore, many patients undergoing this type of radiation therapy report minimal side effects during the first few days of treatment and continue going to work, as usual.
Hyperfractionated radiotherapy can be combined with intrabiliary brachytherapy, which is a type of radiation treatment that uses small pellets of radioactive material placed into the bile duct for a short time.
This combination therapy used by the Cleveland Clinic in the United States has reported a success rate of 70 to 80 percent in completely destroying the PC.
These patients are admitted for three days and given high-dose brachytherapy via a one access catheter that is placed in the right bile duct and another in the left bile duct, with the radioactive pellets placed inside both catheters. The source delivers radiation at 10-15 different positions inside the tumor, and the tumor ultimately receives a very large cumulative dose of radiation.
Throughout the 30 doses of external hyper-fractionated radiation by IMRT, radiation-sensitizing chemotherapy is also given. Chemotherapy is not given during brachytherapy but is then reintroduced while the patient awaits liver transplant, which is the final treatment step.
However, long term effect of radiotherapy can cause shrinking of the bile ducts and hence a liver transplant is inevitably required even in the absence of the cancer tissue. Liver transplant further adds to the high chance of survival in patients with PC. It is therefore necessary that patients diagnosed with PC are referred to a highly specialized centre, which offers multidisciplinary care and a high-volume liver transplant unit.