At 3 years , elective node dissection resulted in an improved rate of overall survival ( 80.0 % ; 95 % confidence interval [ CI ] , 74.1 to 85.8 ) , as compared with therapeutic dissection ( 67.5 % ; 95 % CI , 61.0 to 73.9 ) , for a hazard ratio for death of 0.64 in the elective-surgery group ( 95 % CI , 0.45 to 0.92 ; P = 0.01 by the log-rank test ) .