Tests that a doctor can perform if symptoms of colon cancer are present include a colonoscopy, fecal occult blood tests to check for blood in the stool, and imaging tests such as a CT scan, according to WebMD. Additional colon cancer screenings are a double-contrast barium enema and a sigmoidoscopy.
A double-contrast barium enema involves an x-ray, and a sigmoidoscopy is similar to a colonoscopy, as noted by the National Cancer Institute. The type of testing undertaken depends on many factors, including the patient's age, genetic background and the preparation necessary for the screening. It is important to contact a doctor when the earliest symptoms appear.