Assessment on the potential role of applying cryoprobe for tissue ablation

Depth of injury caused by liquid nitrogen cryospray: study of human patients undergoing planned esophagectomy

BACKGROUND

Cryotherapy using liquid nitrogen delivered endoscopically has been used for mucosal ablation of esophageal neoplasia. There are no data for the human esophagus on the depth of injury and effects of this technique.

AIM

Prospective study to examine the effect of treatment and depth of injury to the human esophagus of liquid nitrogen spray cryotherapy for subjects with esophageal neoplasia before planned esophagectomy.

METHODS

Liquid nitrogen spray cryoablation was performed seven days before scheduled esophagectomy for seven males with esophageal carcinoma. Subjects were assigned to either treatment of four cycles of 10 s each (group 1) or two cycles of 20 s each (group 2) applied to a 2-cm segment of healthy esophagus above the tumor area. Main outcomes measured were: mean depth of injury (mm); surface displaying mucosal ablation, and adverse events.

RESULTS

Mucosal destruction was similar for both groups (group 1, 95%; group 2, 93%; p = NS). Deeper injury was observed for group 2; mean depth was 5.4 mm compared with 4.0 mm for group 1. Cryonecrosis reached the submucosa for 60% (12/20) of subjects in group 1 versus 93% (14/15) of subjects in group 2 (p = 0.04, two-tailed Fisher's exact test). No serious adverse events occurred. No perforation was seen in the resected esophagus.

CONCLUSION

Mucosal ablation with liquid nitrogen spray cryotherapy was highly effective in inducing mucosal necrosis; the doses assessed had similar effects. Ablation reached the submucosa more often with longer spray time despite fewer treatment cycles.