External beam radiation treatment of intrahepatic cholangiocarcinoma: a narrative review

Abstract

This narrative review aims to summarize the currently available evidence for the role of radiation in the treatment of intrahepatic cholangiocarcinoma (ICC). ICC is the second most common primary liver cancer after hepatocellular carcinoma (HCC). It is an aggressive tumor with a high mortality due to its refractory nature and often presenting as advanced disease. There remains some controversy over the role of radiotherapy in the adjuvant and definitive setting. We performed a systemic search of MEDLINE/PubMed and ClinicalTrials.gov databases, focusing on those published in the last 20 years. Our search queried “intrahepatic cholangiocarcinoma radiotherapy” and was limited only to clinical trials, meta-analyses, and retrospective studies, omitting books, documents, and reviews. Our search resulted in 55 references. These were manually reviewed, and only 20 references were within our scope of interest ranging from 2002–2018. The role of radiation is discussed in the adjuvant and definitive setting. In the adjuvant setting, there is a lack of level 1 evidence for adjuvant radiation for ICC after surgical resection. However, based on NCCN guidelines, radiation may be considered in R1 and node-positive disease. In the definitive setting, doublet chemotherapy with gemcitabine and cisplatin should be followed by locoregional treatment depending on disease characteristics. For small peripherally located tumors, stereotactic body radiation therapy (SBRT) has favorable outcomes. For large tumors abutting critical structures, conventional or ablative hypofractionated radiation is preferable to minimize toxicities. An effective multidisciplinary approach is the optimal strategy for achieving the best outcomes in patients with ICC.