Evaluation of response after stereotactic body radiotherapy for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is increasing in incidence due to hepatitis C. Stereotactic body radiotherapy (SBRT) is a noninvasive, effective therapy in the management of liver malignancies. The authors evaluated radiological response in 26 patients with HCC treated with SBRT at Indiana University.

Between March 2005 and June 2008, 26 patients with HCC who were not surgical candidates were enrolled in a phase 1 to 2 trial. Eligibility criteria included solitary tumors ≤ 6 cm or up to 3 lesions with sum diameters ≤ 6 cm, and well-compensated cirrhosis. All patients had imaging before, at 1 to 3 months, and every 3 to 6 months after SBRT.

Patients received 3 to 5 fractions of SBRT. Median SBRT dose was 42 Gray (Gy) (range: 24-48 Gy). Median follow-up was 13 months. Per Response Evaluation Criteria in Solid Tumors (RECIST), 4 patients had a complete response (CR), 15 had a partial response (PR), and 7 achieved stable disease (SD) at 12 months. One patient with SD experienced progression marginal to the treated area. The overall best response rate (CR + PR) was 73%. In comparison, by European Association for the Study of the Liver (EASL) criteria, 18 of 26 patients had ≥ 50% nonenhancement at 12 months. Thirteen of 18 demonstrated 100% nonenhancement, being > 50% in 5 patients. Kaplan-Meier 1- and 2-year survival estimates were 77% and 60%, respectively.

SBRT is effective therapy for patients with HCC with an overall best response rate (CR + PR) of 73%. Nonenhancement on imaging, a surrogate for ablation, may be a more useful indicator than size reduction in evaluating HCC response to SBRT in the first 6 to 12 months, supporting EASL criteria.