Ablation reduced the risk of progression to high-grade dysplasia or adenocarcinoma by 25.0 % ( 1.5 % for ablation vs 26.5 % for control ; 95 % CI , 14.1 % -35.9 % ; P < .001 ) and the risk of progression to adenocarcinoma by 7.4 % ( 1.5 % for ablation vs 8.8 % for control ; 95 % CI , 0 % -14.7 % ; P = .03 ) .