The process used to find out if cancer has spread within the colon or to other parts of the body is called staging. The information gathered from the staging process determines the stage of the disease. It is important to know the stage in order to plan treatment.The following tests and procedures may be used in the staging process: 1  CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, such as the abdomen, pelvis, or chest, taken from different angles. Chest x-ray: An x-ray of the organs and bones inside the chest. 2  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. 3  Surgery: A procedure to remove the tumor and see how far it has spread through the colon.