Endoscopic biopsy of a gastric ulcer patient turns out to be malignancy. What is your next step?

Once a malignancy is established, investigations are required to stage the disease and to know operability.USG has limited role in staging. CT is used for staging. Preoperative laparoscopy is done as small peritoneal metastasis might be missed in CT. Ca 19-9 is useful in pancreatic cancer, its more useful as a prognostic indicator than for diagnosis.Bailey and love 27e pg 1136