Selective internal radiation therapy for liver metastases from colorectal cancer

Liver metastases are often the dominant site of metastatic disease in colorectal cancer. Selective internal radiation therapy (SIRT) involves embolising radiolabeled spheres (SIR-Spheres) into the arterial supply of the liver. This review assesses the effectiveness and toxicity of SIRT in the treatment of metastatic colorectal cancer liver metastasis when given alone or with systemic or regional hepatic artery chemotherapy. We reviewed only randomised controlled trials comparing SIRT and chemotherapy (systemic and/or regional) with chemotherapy alone, or comparing SIRT alone with best supportive care. Only four randomized trials were identified. Due to heterogeneity of the patients and treatments received it was not possible to perform a formal meta-analysis, therefore this is a descriptive analysis only. All studies included patients with either liver only or liver dominant metastatic colorectal cancer. Two trials compared SIRT alone and SIRT with chemotherapy first line. The first with only 21 patients revealed a significant improvement in PFS and median survival with SIRT. The larger second study SIRFLOX of 530 patients comparing SIRT and current standard first line FOLFOX chemotherapy (+/−  bevacizumab) with standard FOLFOX +/− bevacizumab alone. There was no improvement in overall PFS with addition of SIRT. In chemotherapy refractory patients SIRT and systemic chemotherapy (fluorouracil) improved progression free survival but not overall survival. A final study (63 patients) compared SIRT and regional chemotherapy (floxuridine) with regional chemotherapy alone in first line showed no significant difference in progression free survival and median survival. There remains a lack of evidence that SIRT improves survival or quality of life in patients with metastatic colorectal cancer. The overall survival results from SIRFLOX combined with FOXFIRE and FOXFIRE Global are awaited.