Purpose: Intrahepatic cholangiocarcinomas (IHC) are rare tumors for which large randomized studies regarding the use of radiation are not available. The purpose of this study was to examine the role of adjuvant and definitive radiation therapy in the treatment of IHC in a large group of patients.
Methods and materials: This is a retrospective analysis of 3,839 patients with IHC collected from the Surveillance, Epidemiology, and End Results (SEER) database. The primary endpoint was overall survival (OS).
Results: Patients received either surgery alone (25%), radiation therapy alone (10%), surgery and adjuvant radiation therapy (7%) or no treatment (58%). The median age of the patient population was 73 years (range, 22-102 years); 52% of patients were male and 81% were Caucasian. Median OS was 11 (95% confidence interval [CI], 9-13), 6 (95% CI, 5-6), 7 (95% CI, 6-8), and 3 months for surgery and adjuvant radiation therapy, surgery alone, radiation therapy alone, and no treatment, respectively. The OS was significantly different between surgery alone and surgery and adjuvant radiation therapy (p = 0.014) and radiation therapy alone and no treatment (p < 0.0001). Use of surgery and adjuvant radiation therapy conferred the greatest benefit on OS (HR = 0.40; 95% CI, 0.34-0.47), followed by surgery alone (hazard ratio [HR], 0.49; 95% CI, 0.44-0.54) and radiation therapy alone (HR, 0.68; 95% CI, 0.59-0.77) compared with no treatment, on multivariate analysis. Propensity score adjusted hazard ratios (controlling for age, race/ethnicity, stage, and year of diagnosis) were also significant (surgery and adjuvant radiation therapy vs. surgery alone (HR, 0.82; 95% CI, 0.70-0.96); radiation therapy alone vs. no treatment (HR, 0.67; 95% CI, 0.58-0.76)).
Conclusions: The study results suggest that adjuvant and definitive radiation treatment prolong survival, although cure rates remain low. Future studies should evaluate the addition of chemotherapy and biologics to the treatment of IHC.