Stereotactic Body Radiation Therapy for Liver Metastases and Primary Hepatocellular Carcinoma: Normal Tissue Tolerances and Toxicity

BACKGROUND: There is growing interest in stereotactic body radiation therapy (SBRT) as a noninvasive means of treating inoperable hepatic metastases and primary intrahepatic hepatobiliary carcinomas. While initial outcomes are encouraging, the safety of delivering such large, ablative doses is still being studied. METHODS: We compiled all dose-volume constraints from seven prospective trials of liver SBRT and linked them to reported toxicities. Dose thresholds were made isoeffective, and grade 3 or higher toxicities for liver and adjacent normal tissues were correlated. RESULTS: Four cases of grade 3-5 radiation-induced liver disease (RILD) were identified, including 1 treatment related death, from all patients treated for metastasis. Three of these 4 cases were linked to excessive radiation doses in a large volume of liver. In 56 patients treated for hepatocellular carcinoma (HCC), 1 case of grade 5 RILD and 2 cases of grade 2 hepatic toxicity were reported. Additionally, a prominent retrospective series reported 3 cases of grade 5 RILD in 9 patients treated for HCC. CONCLUSIONS: SBRT appears to be safe for treatment of hepatic metastasis. The use of SBRT for HCC should be undertaken with caution or within the context of a clinical trial. Strict adherence to reported dose-volume constraints is advocated.