Staging is the process used to find out how far the cancer has spread. The information gathered from the staging process determines the stage of the disease. In order to plan treatment, it is important to know the extent of the disease and whether the tumor can be removed by surgery. The following tests and procedures may be used:Gastrointestinal endoscopy: A procedure to look inside the gastrointestinal tract for abnormal areas or cancer. An endoscope is inserted through the mouth and esophagus into the stomach and first part of the small intestine. Also, a colonoscope is inserted through the rectum into the colon, this is called colonoscopy. CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. Somatostatin receptor scintigraphy (SRS): A type of radionuclide scan used to find carcinoid tumors. In SRS, radioactive octreotide, a drug similar to somatostatin, is injected into a vein and travels through the bloodstream. The radioactive octreotide attaches to carcinoid tumor cells that have somatostatin receptors. A radiation-measuring device detects the radioactive material, showing where the carcinoid tumor cells are in the body. Biopsy: The removal of cells or tissues so they can be viewed under a microscope to check for signs of cancer. Angiogram: A procedure to look at blood vessels and the flow of blood. A contrast dye is injected into the blood vessel. As the contrast dye moves through the blood vessel, x-rays are taken to see if there are any blockages. PET scan (positron emission tomography scan): A procedure to find malignant tumor cells in the body. A small amount of radionuclide glucose is injected into a vein. The PET scanner rotates around the body and makes a picture of where glucose is being used in the body. Malignant tumor cells show up brighter in the picture because they are more active and take up more glucose than normal cells. X-ray of the abdomen: An x-ray of the organs and tissues inside the abdomen. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.
This answer is based on source information from the National Cancer Institute.