With an overall median follow-up of 20.7 months ( 95 % CI 17.9-25 .6 ) and 123 ( 58 % ) of 212 required events observed , progression-free survival was significantly shorter in the chemotherapy plus cetuximab group than in the chemotherapy alone group ( 14.1 months [ 95 % CI 11.8-15 .9 ] vs 20.5 months [ 95 % CI 16.8-26 .7 ] , hazard ratio 1.48 , 95 % CI 1.04-2 .12 , p = 0.030 ) .