Prolonged survival with ablative RT in inoperable intrahepatic cholangiocarcinoma

Last Updated: 2015-10-30

By Will Boggs MD

NEW YORK (Reuters Health) - Patients with inoperable intrahepatic cholangiocarcinoma who receive ablative radiotherapy have prolonged survival, according to a new retrospective study.

"Ablative radiation doses given over 3 to 5 weeks with a stereotactic technique leads to durable local tumor control and a 2- to 3-year median survival benefit for patients with intrahepatic cholangiocarcinoma," Dr. Christopher H. Crane from The University of Texas MD Anderson Cancer Center in Houston told Reuters Health by email.

Prior studies suggested that radiotherapy for inoperable intrahepatic cholangiocarcinoma (IHCC) can improve local control and prolong survival. But the role of radiotherapy in its definitive treatment remains controversial, Dr. Crane and colleagues note in the Journal of Clinical Oncology, online October 26.

The team evaluated the influence of radiotherapy dose escalation on local control and overall survival in 79 patients with inoperable IHCC, focusing on whether a threshold radiotherapy dose is associated with a survival benefit.

Radiotherapy was individualized with the goal of achieving the highest minimum biologic equivalent dose (BED) to the tumor while protecting at-risk organs, they explain in their report.

The BED for the median radiotherapy dose per fraction was 80.5 Gy, well above the conventional 50.4 Gy. The median radiotherapy dose delivered to central tumors was 58.05 Gy in 15 fractions, and the median dose delivered to peripheral tumors was 60 Gy in 30 fractions.

Patients treated with BED greater than 80.5 Gy had a three-year local control rate of 78% versus 45% for those treated with a lower BED.

Median survival was 43 months for those treated with doses higher than the conventional 50.4 Gy, but only 23 months for patients treated with 50.4 Gy or less.

Median overall survival was not reached for patients treated with BED greater than 80.5 Gy and was 27 months for those treated with 80.5 Gy or less.

Two- and three-year overall survival rates were 73% for patients treated with BED greater than 80.5 Gy, compared with 58% at two years and 38% at three years for patients treated with BED of 80.5 Gy or less.

Radiation dose was the only significant predictor of both local control and overall survival on multivariable analysis.

There were no reports of radiation-induced liver disease, and no patients developed liver failure in the absence of IHCC progression.

"This study shows that lower doses of radiation are not as effective," Dr. Crane said. "Ablative doses are necessary and are only possible in these large tumors if treatment courses are at least 3 weeks, due to the need to protect the liver, stomach, duodenum, and colon optimally. The standard one-week SBRT (Stereotactic Body Radiation Therapy) is not optimal to deliver ablative doses in the majority of these cases."

"Specific solutions to the problem of organ motion and high-quality image guidance are necessary to deliver this treatment," Dr. Crane explained. "There is a significant learning curve for radiation oncologists. The preferred option for patients is enrollment on NRG GI 001, a trial that offers the opportunity to answer this question (whether ablative radiotherapy should be the treatment of choice) as well as provide prospective quality assurance for individual cases."

SOURCE: http://bit.ly/1NEJr4X

J Clin Oncol 2015.