Use of an anti-reflux catheter to improve tumor targeting for holmium-166 radioembolization. A prospective, within-patient randomized study

The objective of this study was to investigate whether the use of an anti-reflux catheter improves tumor targeting for colorectal cancer patients with unresectable, chemorefractory liver metastases (mCRC) treated with holmium-166 (${}^{166}$Ho)-radioembolization. In this perspective, within-patient randomized study, left and right hepatic perfusion territories were randomized between infusion with a Surefire{/circledR} anti-reflux catheter or a standard microcatheter. The primary outcome was the difference in tumor to non-tumor (T/N) activity distribution. Secondary outcomes included the difference in infusion efficiency, absorbed doses, predictive value of ${}^{166}$-scout, dose-response relation, and survival. Twenty-one patients were treated in this study (the intended number of patients was 25). The median T/N activity concentration ratio with the use of the anti-reflux catheter was 3.2 (range 0.9-8.7) versus 3.6 (range 0.8-13.3) with a standard microcatheter. There was no difference in infusion efficiency (0.04% vs. 0.03% residual activity for the standard microcatheter and anti-reflux catheter, respectively) (95%CI - 0.05-0.03). No influence of the anti-reflux catheter on the dose-response rate was found. Median overall survival was 7.8 months (95%CI 6-13). Using a Surefire{/circledR} anti-reflux catheter did not result in a higher T/N activity concentration ratio in mCRC patients treated with ${}^{166}$-radioembolization, nor did it result in improved secondary outcomes measures.