Renal effects of microwave ablation compared with radiofrequency, cryotherapy and surgical resection at different volumes of the liver treated

Background: Renal changes after microwave tissue ablation (MTA) were compared with those following hepatic resection, cryotherapy (CRYO), and radiofrequency ablation (RFA). Structural damage producing renal impairment has been assessed directly by examining tissue specimens and by serum analysis for two sensitive biomarkers, retinol binding protein (RBP) and the heat shock protein 70 (HSP-70) for each modality at different ablation volumes. Methods: Live rats underwent MTA, surgical resection, CRYO or RFA of 15, 33 or 66% of total hepatic volume. Urine and tissue samples were collected at the time of death. Percentage of tubules with casts and glomerular damage, tissue expression of HSP-70 and urine RBP were evaluated and compared. Behaviour of the animals was also assessed by means of five different parameters and combined to produce a response score. Results: All RFA and CRYO rats undergoing 66% died and these animals had 460% of damaged tubuli and 8% of altered glomeruli. No animals treated by MTA or surgical resection died. Cut-off values (those predicting fatal treatments) could be identified for levels of HSP-70 and RBP. Conclusions: Large volume MTA is associated with a significant reduced renal damage and is well tolerated compared with RFA and CRYO.