<prompt> Answer this question truthfullyWhat diagnostic tests are used to help with TNM staging and confirm a patient with gastric cancer is a surgical candidate ro distant mets after a diagnosis is made via endoscopy?  <response>: <reason> Once a diagnosis of gastric cancer is made via endoscopy, endoscopic US is used to help with TNM staging and abdominal CT is used to confirm the patient is a surgical candidate ro distant mets. 