External radiation treatment of malignant liver disease: A critical review

Introduction: Owing to the liver's integral role in biosynthesis and homeostasis, management of primary and secondary malignancies arising in this organ is of paramount oncologic significance. Over the past several decades, substantial progress has been achieved in the imaging and treatment of early and advanced hepatic malignancies. Radiation therapy (RT) has recently emerged as one of many local therapeutic options for both primary and metastatic liver cancer. Recent phase I and II studies describe promising efficacy and side effect profile; however, phase III studies are needed to establish RT among standard of care therapeutic modalities. Purpose: In this review, we will describe (a) the scope, epidemiology, and standard treatment options for liver cancer; (b) relevant diagnostic imaging techniques; and (c) provide an in-depth review of RT treatment techniques, dose-volume limits of normal tissues, and results of both conventional and hypofractionated RT liver trials pertaining to primary and secondary liver cancers with emphasis on three-dimensional conformal radiation therapy (3DCRT) and stereotactic body radiotherapy (SBRT) studies.