A significantly lower proportion of patients with MMR-proficient tumors with mutant BRAF ( hazard ratio = @ ; @ % confidence interval : @-@ @ ; Padjusted = @ ) or mutant KRAS ( hazard ratio = @ ; @ % confidence interval : @-@ @ ; Padjusted < @ ) survived disease-free for @ years compared with patients whose MMR-proficient tumors lacked mutations in either gene .