CHICAGO–The addition of selective internal radiation therapy (SIRT) to standard chemotherapy failed to improve overall progression-free survival as first-line treatment of patients with non-resectable colorectal cancer liver metastases, according to research presented at the 2015 American Society of Clinical Oncology (ASCO) annual meeting in Chicago, IL. However, median liver progression-free survival was significantly prolonged.

For the international, multicenter, open-label, controlled SIRFLOX study, researchers enrolled 530 chemotherapy-naïve patients with non-resectable, liver-only or liver-dominant metastatic colorectal cancer.

Patients were randomly assigned to receive mFOLFOX6 with or without bevacizumab (Arm A) or mFOLFOX6 plus SIRT administered once with cycle 1 with or without bevacizumab in cycle 4 until disease progression.

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Results showed that at a median follow-up of 36.1 months, median overall progression-free survival was 10.2 months in arm A versus 10.7 months in arm B (HR=0.93; 95% CI: 0.77,1.12; P=0.43). Median liver progression-free survival was 12.6 months and 20.5 months in arms A and B, respectively (HR=0.69; 95% CI: 0.55,0.90; P=0.002).

The overall response rate was 68.0% in arm A compared to 76.4% in arm B (P=0.113), and the hepatic response rate was 68.8% and 78.7%, respectively (P=0.042).

In regard to safety, grade 3 or higher adverse events occurred in 73.4% of patients in arm A versus 85.4% of those in arm B. The most common toxicities were hematologic and gastrointestinal in both groups.

“The addition of SIRT, using Y-90 resin microspheres, to FOLFOX-based first-line chemotherapy in patients with liver-dominant metastases did not improve overall progression-free survival,” said principal investigator Peter Gibbs, MBBS, MD, FRACP, of The Royal Melbourne Hospital in Melbourne, Australia.

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“However, it achieved a 7.9 month improvement in median progression-free survival in the liver, representing a 31% reduction in risk of disease progression in the liver with no negative impact on duration of systemic therapy, and had toxicities that were acceptable and as predicted,” Dr. Gibbs concluded.

Analyses on overall survival using data from SIRFLOX and two other ongoing trials in this disease setting are being conducted.


  1. Gibbs P, Heinemann V, Sharma NK, et al. SIRFLOX: Randomized phase III trial comparing first-line mFOLFOX6 ± bevacizumab (bev) versus mFOLFOX6 + selective internal radiation therapy (SIRT) ± bev in patients (pts) with metastatic colorectal cancer (mCRC). J Clin Oncol. 2015;33:(suppl; abstr 3502).