External beam
radiotherapy has historically played a minor role in the primary treatment of
hepatocellular carcinoma. Although there is evidence for
tumor response to external beam
radiotherapy and despite the fact that a radiation dose-response relationship has been established, the limited radiation tolerance of the adjacent normal liver has prohibited wider use of
radiation therapy in this disease. Recent technological and conceptual developments in the field of
radiation therapy-such as intensity-modulated
radiation therapy, image-guided radiation therapy, and stereotactic body
radiation therapy-have the potential to improve
radiation treatments by conforming the delivered radiation dose distribution tightly to the
tumor or target volume outline while sparing normal liver tissue from high-dose radiation. Image guidance allows for a reduction of added (normal tissue) safety margins designed to account for interfraction patient and target setup variability, and stereotactic targeting will further reduce residual target setup uncertainty. Combining improvements in
tumor targeting with normal tissue sparing, radiation dose delivery will enable clinically effective and safe radiation delivery for liver
tumors such as
hepatocellular carcinoma. This article reviews the role of
radiotherapy for
hepatocellular carcinoma; presents modern
radiation therapy modalities and concepts such as intensity-modulated, image-guided, and stereotactic body
radiation therapy; and hypothesizes about their future effect on primary treatment alternatives.