Experience with stereotactic radiation therapy for liver oligometastases of colorectal cancer

Introduction: The problem of treating patients with unresectable liver metastases of colon cancer is currently far from being solved. One possible approach is the use of stereotactic body radiotherapy. The purpose of this study was to evaluate the immediate and long-term results of stereotactic radiotherapy in patients with colorectal cancer and oligometastatic liver metastases. Methods: This study was designed as a retro-prospective, open-label, controlled, non-randomized clinical trial. We assessed one-year local control, one-year overall survival, progression-free survival, and toxicity in 60 patients with oligometastatic liver disease from colorectal cancer who underwent stereotactic body radiotherapy, with median dose of 54 Gy. Results: The median follow-up was 20,1 months. One-year local control (LC) was 73,7% (95% CI = 62,7-86,6%). One-year overall survival (OS) was 92,8% (95% CI = 86,3-99,9%), one-year progression-free survival (PFS) was 31,3% (95% CI = 21,1-46,4%) with a median of 8,1 months. Grade > 3 toxicity was not noted. No cases of radiation-induced liver failure were observed. Radiation dose (HR=0.88, 95% CI = 0.81-0.95, p = 0.00087), metastasis size (HR=1.51, 95% CI = 1.07-2.12, p = 0.01858) and their number (HR = 1.8, 95% CI = 1.01-3.22, p = 0.04669) are significant risk factors for LC. Metastasis size>3 cm is a significant risk factor for LC (HR = 5.5, 95% CI = 1.7-17.9, p = 0.005) and OS (HR=3.8, 95% CI = 1.3-11.7, p = 0.02). Conclusion: Stereotactic body radiotherapy is an effective and safe method of providing local control of oligometastatic liver metastases in colorectal cancer as part of a combined treatment approach. Further studies are required to individualize the indications for this treatment method.