REAL3 Trial of Efficacy of EOX With/Without Panitumumab in Previously Untreated Adv OG Cancer

Inclusion Criteria: * Histologically verified inoperable locally advanced or metastatic adenocarcinoma or undifferentiated carcinoma of the oesophagus, oesophago-gastric junction, or stomach. * Slides of tumour tissue should be available for centralised EGFR staining * Uni-dimensionally measurable disease (CT or MRI as per RECIST). * No prior chemotherapy including previous adjuvant chemotherapy * No prior radiotherapy including adjuvant radiotherapy. Patients receiving palliative radiotherapy to sites of disease that are not measurable may be eligible and should be discussed with the Chief Investigator. * Male/female patients aged ≥18 years. * WHO Performance status 0, 1 or 2. * Patients should have a projected life expectancy of at least 3 months. * Completion of baseline quality of life questionnaire (EORTC QLQ C30). * Adequate cardiac function; formal measurement of left ventricular ejection fraction is only required if clinically indicated. * Adequate bone marrow function: absolute neutrophil count (ANC) ≥1.5x109/l; white blood cell count ≥ 3x109/l; platelets ≥ 100x109/l; haemoglobin (Hb) ≥ 9g/dl (can be post-transfusion). * Adequate renal function: calculated creatinine clearance ≥50ml/minute. * Adequate liver function: serum bilirubin ≤1.5x ULN; ALT/AST ≤2.5x ULN; ALP ≤3x ULN (in the absence of liver metastases). If liver metastases are present, serum transaminases ≤5x ULN are permitted. * Written informed consent must be obtained from the patient before any study-specific procedures are performed (see Section 12.0). Note: Epidermal growth factor receptor (EGFR) positivity by immunohistochemistry will not be required for study entry. Slides obtained from previously collected paraffin embedded archived specimens will be collected centrally for EGFR staining. A multivariate analysis will then be performed to exclude any effects of EGFR status on outcome measures Exclusion Criteria: * Tumours of squamous histology. * Patients with locally advanced oesophageal cancer suitable for definitive chemoradiotherapy. * Documented or symptomatic brain metastases and/or central nervous system metastases or leptomeningeal disease. * Previous chemotherapy or radiotherapy. See Inclusion criteria for note regarding palliative radiotherapy. * Any major surgery within 4 weeks prior to the start of study treatment. * Any prior treatment with an EGFR signal transduction directed therapy. * Treatment with non-permitted medication. * Clinically significant (i.e. active) cardiac disease e.g. symptomatic coronary artery disease, uncontrolled cardiac dysrhythmia, or myocardial infarction within the last 12 months. Patients with any history of clinically significant cardiac failure are excluded from study entry. * History of interstitial lung disease (e.g., pneumonitis or pulmonary fibrosis) or evidence of interstitial lung disease on baseline chest CT scan. * Known peripheral neuropathy \>Grade 1 (absence of deep tendon reflexes as the sole neurological abnormality does not render the patient ineligible). * Lack of physical integrity of the upper gastro-intestinal tract, malabsorption syndrome, or inability to take oral medication (administration of capecitabine by naso-gastric or jejunostomy feeding tube is permitted). * Known dihydropyrimidine dehydrogenase (DPD) deficiency. * Known hypersensitivity to panitumumab, components of the EOX regimen, or any of the constituents of these agents. * Known positive tests for human immunodeficiency virus (HIV) infection, hepatitis C virus, acute or chronic active hepatitis B infection. * Other clinically significant disease or co-morbidity which may adversely affect the safe delivery of treatment within this trial. * Female patients who may be pregnant or breastfeeding. Potential female patients of childbearing potential must have a negative pregnancy test within 7 days prior to randomisation, or have had amenorrhea for more than 2 years. * Patients of child-bearing potential not consenting to use adequate contraceptive precautions or abstinence during the course of the study and for 6 months after the last study drug administration for females, and 1 month for males. * Any other malignancies within the last 5 years (other than curatively treated basal cell carcinoma of the skin and/or in situ carcinoma of the cervix). * Treatment with another investigational agent within 30 days of commencing study treatment.