After a median follow-up of 11.6 months , disease progression or death occurred in 22 of the 138 patients in the treatment-interruption group and in 12 of the 132 patients in the control group ( P = 0.01 ) , with a hazard ratio of 2.57 ( 95 percent confidence interval , 1.2 to 5.5 ) for the treatment-interruption group .
