Usefulness of robotic radiosurgery for local control of unresectable multiple liver metastases from colorectal cancer: preliminary results

The median survival of untreated patients with liver metastases ranges between 6 and 18 months, but unfortunately surgery may be performed in only 20% of cases. The aim of this preliminary study was to evaluate the usefulness of CyberKnife_ (Accuray Inc, Sunnyvale, CA) image-guided robotic stereotactic radiosurgery for local control of unresectable liver metastases. Patients and Methods: Eight-teen consecutive patients with liver metastases from colorectal cancer, considered unsuitable for surgery, confirmed by ultrasound- or CTguided biopsy or ultrasound-guided FNAB, were enrolled in the study. There were 11 men and 7 women, with an overall median age of 59 years (range 49-73 years). The inclusion criteria were: age between 50-75, no chemotherapy during the last 30 days, acceptable liver function (ALT and ALT<150 U/L, PT>2.5%), Karnofsky performance score <3, no extra-hepatic disease on 18-FDG CT-PET, tumor size and estimated residual liver volume on CT-scan <6 cm and > 700 mL, respectively. Results: The overall tumor volume ranged from 25 to 185 mL (median 70 mL), and the irradiated volume was 18±10 mL (range 11-40 mL). The mean post-treatment followup was 11 months. Inhibition of growth or a reduction in size was obtained in 12 of 18 patients: 5 with complete response, and 7 with partial response. There was a local complete response with other single lesions appearing in two patients, and a progressive disease in 4. Among responders, the median post-treatment volume of the tumor was 22 mL (range 5-55mL), with an overall reduction rate of more than 70%. Toxic events were observed in 11 patients: transient hepatic dysfunction was evident in 7, and pleural effusion, pulmonary embolism, partial portal vein thrombosis, and upper gastrointestinal tract bleeding in one patient each. Three patients with progressive disease died during follow-up, both developing severe liver failure. Conclusions: Using stereotactic radiosurgery a good local control of the disease may be achieved, with limited toxicity. This promising treatment strategy should be further studied in larger series, representing an acceptable alternative in patients with liver metastases unsuitable for surgery.