Adjuvant radioimmunotherapy after radiofrequency ablation of colorectal liver metastases in an experimental model

Abstract

PURPOSE: Radiofrequency ablation (RFA) has shown to improve survival in patients not eligible for surgical resection of colorectal liver metastases. However, recurrences after RFA are a major problem. Adjuvant radioimmunotherapy (RIT) after surgical resection of liver metastases has shown to improve survival. The aim of the present study was to test the hypothesis that adjuvant RIT might be an effective way to prevent recurrent liver metastases after RFA in an experimental model. METHODS: Tumours in the liver were induced by intrahepatic injection of 300,000 CC531 cells in male Wag/Rij rats (n = 60). Ten days later, the intrahepatic tumours were treated with RFA. Adjuvant RIT ((177)Lu-labelled monoclonal antibody MG1 at 300 MBq/kg) was administered intravenously either at the day of RFA (day 10) or 7 days later. Control rats received no treatment. Primary endpoint was survival. RESULTS: Administration of (177)Lu-MG1 resulted in a transient decrease in body weight, compared to no adjuvant treatment. However, no other signs of clinical discomfort were registered. Log rank test showed that the survival curves of the groups treated with RIT, either at day 10 or day 17, did not differ significantly from the survival curve of the rats that did not receive adjuvant treatment (P = 0.902). CONCLUSION: This study shows that adjuvant RIT does not increase survival after RFA of colorectal liver metastases in rats.