OMEGCA - Multi-Omics Evaluation of Peritoneal Fluid in Gastroesophageal Cancer

OMEGCA will be a prospective non-interventional and translational cohort study enrolling at least 200 patients with gastroesophageal cancer at hospitals across Victoria and South Australia. Patients who are undergoing routine peritoneal lavage cytology (PLC) and subsequent curative-intent treatment (either upfront surgery or perioperative systemic treatment and surgery) for gastroesophageal cancer will be recruited and the primary goal is to develop a molecular assay to enable accurate peritoneal staging in patients with gastroesophageal cancer. Tumour biopsies, blood and peritoneal lavage fluid will be collected during routine pre-treatment PLC for all patients. 20-30mL of peripheral blood samples will be taken at staging laparoscopy, surgical resection and post surgery in clinic. Tumour tissue (8-12 endoscopic biopies, 4 – 6 in normal saline and 4 – 6 in formalin) will be obtained along with normal stomach and oesophageal tissue (4 – 6 endoscopic biopsies in normal saline) at staging laparoscopy. Peritoneal fluid (15—250ml of 500ml 0.9% saline from 4 quadrants of peritoneal lavage) will be obtained at staging laparoscopy and surgical resection. Re-identifiable data including clinical data, CT and PET data, endoscopy data, histopathological detail and cost data will also be collected along with these samples. Clinical follow up for patients will involve a post operative follow up visit in clinic a post operative and where possible a blood sample will be collected for the purposes of this research. Clinical data obtained as part of routine care at this visit will also be contributed to this research and will be retrieved from medical records. Long term follow up will occur 1 – 5 years after surgery in clinic. Only data obtained for the purposes of routine surveillance will be required for this aspect of the research. Part of the samples obtained will undergo methylomic analysis at Peter MacCallum Cancer Centre, Victoria. The remaining biospecimens will undergo genomic whole exome sequencing analysis at the John Hospkins University Hospital and Haystack Oncology, USA. Both these methods are aimed at detecting the presence of tumour derived DNA in peritoneal fluid. Specifically, methylmoic analysis looks at the molecular markers that are present on the DNA molecule. How the DNA is uniquely marked may be a reflection of cancer specific. Whereas genomic sequencing looks for an error in the genetic code itself and that error is known as a variant. Participant recruitment will occur for 2 years with clinical follow up for 5 years after the last enrolled patient.