In the extended analysis of RAS wild-type tumours ( n = 87 ) , objective response was significantly improved by addition of cetuximab to FOLFOX4 ( 58 % versus 29 % ; odds ratio 3.33 [ 95 % confidence interval 1.36-8 .17 ] ; P = 0.0084 ) ; although limited by population size , there also appeared to be trends favouring the cetuximab arm in terms of PFS and overall survival in the RAS wild-type group compared with the RAS evaluable group .