Stereotactic body radiotherapy dose and its impact on local control and overall survival of patients for locally advanced intrahepatic and extrahepatic cholangiocarcinoma.

Abstract

Non-resectable cholangiocarcinoma (CCC) is a significant therapeutic challenge because of bad prognosis. This study analyzed the outcome after SBRT for intra- and extrahepatic CCC. Sixty-four patients with 82 CCC lesions from a retrospective multicenter database were analyzed. Available parameters were analyzed for local control (LC), overall survival (OS) and toxicity. Median follow-up time for patients alive was 35 months (range 7-91 months). Median overall survival (OS) time was 15 months; 2-year and 3-year OS rates were 32% and 21%. Median prescribed biological effective radiation dose (BED, α/β = 10) was 67.2 Gy₁₀ (range, 36-115 Gy₁₀; SD: 20 Gy₁₀) in median 8 fractions (range, 3-17; 95% CI: 3-12), median BED_max was 91 Gy₁₀. BED was the only prognostic factor for LC and OS. Patients receiving BED_max >91 Gy₁₀ had a median OS of 24 months vs. 13 months for those receiving lower doses (p = 0.008). LC rates at 12 and 24 months were 91% and 80% for BED_max >91 Gy₁₀ vs. 66% and 39% for lower doses (p = 0.009). Of note, tumor size and PTV were neither predictive nor prognostic for LC and OS. Treatment tolerance was good with 17% of grade 1 gastroduodenitis, 11% of grade 2-3 cholangitis and 4.7% of grade 3 gastrointestinal bleeding. This is the largest reported series on SBRT in cholangiocarcinoma. Overall survival and local control were significantly improved after higher doses (BED) and tolerance was excellent.