Background: Whilst perioperative chemotherapy (CT) combined with radical surgery offers a survival benefit over surgery alone in GGOJA, 3-year survival still needs to be improved. The purpose of this phase II study was to evaluate the efficacy and safety of the perioperative use of cetuximab combined with 5-fluorouracil and cisplatin in operable GGOJA. Methods: Untreated operable patients with a WHO Performance Status (PS) ≤ 2 and age ≤ 75 years, with localised GGOJA received 6 cycles of intravenous Cetuximab (500mg/m²), Cisplatine (50mg/m²) and LV5FU2s (folinic acid 400mg/m², 5FU bolus 400mg/m², and continuous infusion of 5FU 2400mg/m²) every 2 weeks. Surgery was planned 3-4 weeks after the end of neaodjuvant CT and postoperative CT planned for 6-8 weeks after surgery. The primary objective was a combined evaluation of tumoral response, assessed by centrally reviewed computed tomography, and major toxicities leading to neoadjuvant CT being discontinued. Sample size (63 patients) was calculated using Bryant and Day design (α=5%, Power=80%), expecting a rate of objective response of 45% and a percentage of patients without major toxicities of 90%. Results: 65 patients were enrolled from 2011 to 2013 with a median age of 60.5 years. 83.1% were men, 98.5% had a WHO PS<2, 30.8% had a gastric and 69.2% a junctional tumour, 28.5% had a stage II and 71.4% of patients a stage III tumour. With regard to the primary endpoint, 64 patients were evaluated, 29.7% (n=19) had an objective morphological tumour response and 95.3% (n=61) did not stop treatment prematurely due to major toxicity. 58 patients (89.2%) completed neoadjuvant CT as planned. The median duration of CT was 2.3 months and grade 3-4-5 toxicities were observed in 61.5% of patients. 60 patients (92.3%) underwent surgical resection with 24 significant complications (41.7%) and 2 postoperative deaths (3.4%). On histological analysis, 40 patients (71.4%) were non responders. Conclusions: Adding cetuximab to the neoadjuvant chemotherapy regimen in operable GGOJA is safe but does not show enough efficacy in the present study to meet the primary endpoint. Clinical trial information: NCT01360086