Patients receiving chemotherapy followed by involved field radiotherapy had a significant benefit on event-free survival ( hazards ratio [ HR ] = 1.47 , 95 % confidence interval [ CI ] : 1.14 to 1.90 ; P = 0.003 ) , but not improved overall survival ( HR = 1.00 , 95 % CI : 0.80 to 1.25 ; P = 0.978 ) at 8 years , in relation to those in the chemotherapy alone arm .