"Surgery and radiotherapy shows an early response benefit. It shows that the addition of radiation is potentially reasonable for the first-line treatment," said Clifton David Fuller, M.D., Ph.D., principal investigator of the study. Fuller is a research associate in radiation medicine at OHSU, and a resident in the Department of Radiation Oncology and trainee in Human Imaging/Radiobiology, Division of Radiological Sciences, University of Texas Health Science Center at San Antonio.
A poster of the study will be presented Oct. 28 at the 2007 annual American Society of Therapeutic Radiology and Oncology (ASTRO) meeting in Los Angeles.
The specific cancer type studied, locoregional extraheptitc cholangiocarcinoma (EHCC), is an uncommon cancer of the bile ducts between the liver and gall bladder. Patients with this cancer typically experience symptoms at advanced stages, and cure rates are low even with aggressive therapy. Patients with this cancer have extremely poor prognosis, with an average five-year survival rate of 5 to 10 percent. The reported incidence of cholangiocarcinoma is one to two cases per 100,000 people in the U.S.
"Because these cases are relatively rare, whether radiation should be added to surgery has remained a matter of debate. Because the numbers have been too small to launch a head-to-head trial, we have sought to determine baseline survival for people with this cancer receiving surgery and radiotherapy using a large data set. This study presents results from the largest population-based data set for patients with this cancer," said Charles Thomas, M.D., co-author of the study, and OHSU chairman of radiation medicine and professor of medicine.
A total of 2,591 cases of cholangiocarcinoma diagnosed from 1973 to 1998 were taken from the Surveillance, Epidemiology and End Results (SEER) program of the National Cancer Institute. Cases were sorted into surgery alone; radiotherapy alone; surgery and radiotherapy; and neither surgery nor radiotherapy.
Researchers found that early survival increased when surgery and radiation were combined. Those receiving both treatments were more likely to survive the first two years after diagnosis, even though the five-year survival remained similar for both groups. The addition of radiation to surgery also was associated with increased median survival.
"We're not sure why this early survival benefit disappears. It could be that radiation delays the progression of the disease, and delays disease progression, but we don't know for sure. However, in the absence of clinical trial data, it is reasonable to suggest radiation plus surgery or surgery alone as the prescribed treatment for this cancer, given our observations. Patients selecting treatment should ask their doctors whether radiation should be added to surgery in their particular cases," Fuller said.