 - Group B 50 patients: 5-FULV panitumumab combination therapy, once every two weeks levofolinate calcium l-LV: 200 mgm2day 1; bolus 5-FU: 400 mgm2day 1; infusional 5-FU: 2400 mgm2day 1-3; panitumumab: 6 mgkg This multi-center trial will be conducted in Japan. The overall time to participate in this study is approximately 12 months. 