Some subtypes of gastric and cardia tumors such as adenocarcinoma or gastric linitis with disseminated cells respond poorly to the pre-operative chemotherapy, and some of them do not respond to chemotherapy usually performed. Doing chemotherapy in these patients could delay their surgical management. The completion of chemotherapy for these patients would be a bad prognosis factor according to recent data from the literature. Therefore, the aim of this research is to find prognostic markers of sensitivity to chemotherapy usually performed. The investigators are going to use biopsies realized at diagnosis and select patients good and bad responders. Primary purpose: To study cardia and gastric tumors, molecular markers sensitivity to pre- and post- perative chemotherapy protocols (EOX protocol ... FOLFOX) or chemoradiation Secondary purposes: * To assess the impact of patients' lifestyle (via a questionnaire) on the response to chemotherapy * To study markers of cancer stem cells * To correlate clinical and molecular markers with patient survival and quality of life questionnaires * To characterize the expression levels (Met, Her2, FGFR2) and mutations (p53 ras) in frequently deregulated genes in gastric cancers. * To characterize the level of expression of predictive candidate markers (ΔNp73, TAp73, HDAC4, mir140, EZH2, CXCL12, CXCR4, CXCR7) found in the literature. * To correlate the abnormalities found in the with tumor stages (before and after chemotherapy) and with 5 years overall survival and progression-free patients