Radiation oncology approaches in liver malignancies

Radiation therapy plays an increasingly important role in the treatment of hepatic malignancies. There is convincing evidence of safety and efficacy employing brachytherapy (yttrium-90), three-dimensional conformal radiotherapy, intensity-modulated radiotherapy, stereotactic body radiotherapy (SBRT), and proton beam therapy (PBT) in all stages of primary and metastatic involvement in the liver. Technologic advances in tumor imaging, real-time tracking of moving targets during radiotherapy delivery, and superb radiation dose deposition control have enabled treatment of previously unapproachable lesions. Recently completed and ongoing clinical trials are refining optimal dose fractionation schedules for SBRT as monotherapy. Radioembolization as part of first-line therapy in metastatic colorectal tumors is being tested in large international trials combined with FOLFOX6 and bevacizumab, as well as in hepatocellular carcinoma with sorafenib. PBT is becoming more available as new facilities open in many countries providing particle beam therapy, which delivers unparalleled control of radiation dose close to critical structures. A major point of research is understanding how best to safely destroy tumors in the background of often fragile hepatic function from cirrhosis or heavily pretreated chemotherapy liver parenchyma. Fortunately, serious complications from radiotherapy are rare, acute toxicities are typically Common Terminology Criteria for Adverse Events v4.0 grade 1-2, with consistent response rates of 50% to 97% in the modern era.