Stereotactic Radiosurgery for Liver Malignancies Using the CyberKnife

22.1 Abstract

Radiotherapy for liver tumors has been limited by the low tolerance of the whole liver to radiation. Improvements in imaging and localizing techniques allow more accurate targeting of radiotherapy. Our Phase I dose escalation study evaluated the safety and feasibility of single-fraction radiosurgery with the CyberKnife® (Accuray Incorporated, Sunnyvale, CA) for patients with primary or metastatic liver malignancies. Patients underwent abdominal CT scans with dual phase contrast to identify lesions and CT-guided percutaneous placement of gold spherical fiducials for targeting purposes. Treatments were delivered with motion tracking using X-ray detection of fiducial and surface light emitting diode positions. The dose was escalated from 18 Gy to 30 Gy increasing in increments of 4 Gy, prescribed to the minimal isodose line that completely encompassed the planning target volume (PTV). Acute gastrointestinal toxicity was scored according to the common toxicity criteria adverse event (CTCAE), version 3. Response to treatment was determined by serial high-resolution CT and PET scanning and/or MRI. Twenty patients were treated to 26 sites at four dose levels. Sixteen patients had metastatic disease involving the liver, 2 patients had hepatocellular carcinoma (HCC), and 2 patients had intrahepatic cholangiocarcinoma (IHCC). The mean treatment volume was 36.0 cm3 (range 0.8–146.6 cm³). With a median follow-up of 7 months (range: 2–30 months), Grade 1 toxicity was reported by 7 patients, consisting of nausea, abdominal pain, fatigue, and fever. Follow-up scans for 19 patients treated to 25 sites have demonstrated interval decrease in size in 17 sites, stable disease in 3 sites, and local progression in 5 sites. Seven lesions exhibited a complete response. Stereotactic radiosurgery to primary or metastatic malignancies of the liver is feasible and safe. We did not reach a liver tolerance dose.