Immediate treatment significantly prolonged progression-free survival compared with deferred treatment ( HR 0.54 , 95 % CI 0.4-0 .73 , p < 0.0001 ) , with 5-year progression-free survival of 47.6 % ( 95 % CI 38.8-55 .9 ) in the immediate treatment group and 31.8 % ( 24.2-39 .6 ) in the deferred treatment group .