Institutional experience in the treatment of colorectal liver metastases with stereotactic body radiation therapy

Aim: To investigate whether the impact of dose escalation in our patient population represented an improvement in local control without increasing treatment related toxicity. Materials and methods: A cohort of consecutive patients with colorectal liver metastases treated with stereotactic body radiation therapy (SBRT) between December 2002 and December 2013 were eligible for this study. Inclusion criteria were a Karnofsky performance status ≥80% and, according to the multidisciplinary tumor board, ineligibility for surgery or radiofrequency ablation. Exclusion criteria were a lesion size>6. cm, more than 3 metastases, and treatment delivered with other fractionation scheme than 3 times 12.5. Gy or 16.75. Gy prescribed at the 65-67% isodose. To analyze local control, CT or MRI scans were acquired during follow-up. Toxicity was scored using the Common Toxicity Criteria Adverse Events v4.0. Results: A total of 40 patients with 55 colorectal liver metastases were included in this study. We delivered 37.5. Gy to 32 lesions, and 50.25. Gy to 23 lesions. Median follow-up was 26 and 25 months for these two groups. Local control at 2 and 3 years was 74 and 66% in the low dose group while 90 and 81% was reached in the high dose group. No significant difference in local control between the two dose fractionation schemes could be found. Grade 3 toxicity was limited and was not increased in the high dose group. Conclusions: SBRT for colorectal liver metastases offers a high chance of local control at long term. High irradiation doses may contribute to enhance this effect without increasing toxicity