Assessment of response to therapy in hepatocellular carcinoma

The appropriate use of conventional or potential treatments for hepatocellular carcinoma requires that benefit can be shown. Therefore, the accurate assessment of response is both critical and essential. Demonstration of benefit observed will be determined by the criteria used. However, the use of conventional criteria based on anatomical imaging to assess response and progression is inadequate. Limitations occur due to the unique nature, presentation, and course of hepatocellular cancer, any underlying concomitant disease, the multiplicity of treatment options, and the challenges in assessing viable tumor. Locoregional therapies or cytostatic therapies can have beneficial effects and induce tumor necrosis without appreciable changes in tumor size. In recognition of the inherent limitations in conventional imaging criteria, various modifications have been proposed. In this review, the goals of assessing tumor response in clinical practice and in clinical trials are outlined. The varying patterns of response to different therapeutic modalities such as locoregional therapy and molecularly targeted therapy are reviewed, and an approach to the assessment of response based on clinical, biochemical, morphological, and functional criteria has been outlined. The implications of current and proposed approaches of assessing response for clinical practice or design of clinical trials are reviewed.