Phenotyping of Small Bowel Adenocarcinoma

Despite the fact that small intestine makes up 75% of the length of the digestive tract and 90% of its mucosal surface area, small bowel adenocarcinoma (SBA) is rare. SBA is not equally dispatched along the small bowel, a predisposing disease is frequently associated. All these data suggest particular carcinogenesis pathway. SBA carries poor prognosis at all stages and no standard treatment have proved efficacy. So far, no data are available for targeted therapy. From the literature and a previous study of our group some biologic data showed that SBA carcinogenesis is closer to colorectal than gastric carcinogenesis. Nevertheless, some differences arise (ie: low Adenomatous Polyposis Coli mutation rate or frequent DNA mismatch repair deficiency). Even if some trends are founded the prognostic value of molecular alteration and phenotype variation according to small bowel segment, or predisposing disease could not been demonstrate due to small sample size. BIONADEGE study is a planned biologic ancillary study of the NADEGE cohort that enrolled 366 patients with SBA from 2009 to 2012 in France. The tumour blocks and clinical data of 187 patients have been collected. The main objective is to assess the prognostic value for recurrence free survival (RFS) in non-metastatic patients and overall survival (OS) in metastatic patients of molecular alteration in a set of 46 genes and abnormal protein expression potentially implicated in carcinogenesis. The mains secondary objectives are: 1) to identify potential mutation targetable in small intestine tumours and protein expression, 2) to state the frequency of molecular alteration according to the tumour location, stage or predisposing disease and established clinico-biologic correlation. Tissue microarrays will be performed and several potential prognostic markers will be assessed. Sequencing on tumour DNA will investigate the presence of 740 hot spot somatic mutations in 46 genes involved.The abnormal protein expression or t