Cyberknife radiosurgery for liver metastases and primary liver tumors.

Abstract

e14037 Background: Radiosurgery is an emerging radiation technique recently reported for liver metastases and primary liver tumors with encouraging local control rates and the ability to spare normal liver tissue radiation toxicity. Phase I/II trials have been published for radiosurgery to the liver however the trials are small with only 20–70 patients in each trial and various dose schedules reported. We report our experience with Cyberknife radiosurgery for this population of patients. Methods: From 8/2007 to 9/2009, 49 patients with 62 liver tumors were treated with Cyberknife. Thirty patients with 40 tumors were treated with curative doses (defined as BED > 79 Gy10 or 66 Gy in 2 Gy per fraction) and further analyzed. Median follow up for the group is 9 months (range 1–23). 83% of patients were treated for metastatic disease to liver from GI or primary liver cancer. Patients were heavily pretreated prior to radiosurgery (83% chemotherapy, 37% liver directed therapy). The goal of treatment was local control of the liver tumor while preserving adequate liver reserve defined as at least 700 cc receiving ≤ 15 Gy. Results: Median tumor volume was 61 cc. Patients who received previous liver directed therapy had a smaller median liver volume of 1,346 cc vs. 1,638 cc and subsequently had less liver receiving ≤ 15 Gy (1,041 cc vs. 1,215 cc) despite similar tumor volumes (26.9 cc vs. 24.2 cc). Crude local control rate was 90% evaluated by CT/PET in most cases. A dose response was demonstrated with local failure of 3/19 tumors (16%) seen with dose of ≤ 84 Gy10 vs. 0/21 (0%) for > 84 Gy10. Patients with local control had higher liver volume to tumor volume ratio (median 22.7 vs. 8.1) suggesting higher doses were possible because of larger uninvolved liver size and/or smaller tumors. The predominant pattern of failure was distant (63%) both within liver and abdominal/lung metastases. No significant adverse events were noted. Only one patient died secondary to metastatic disease. Conclusions: Cyberknife radiosurgery is an effective modality to treat metastatic disease to liver and primary liver tumors with good local control rates and low morbidity. Future study is necessary with Cyberknife radiosurgery as first-line treatment in combination with chemotherapy for liver metastases. No significant financial relationships to disclose.