Gastrointestinal cancer affects the organs of the digestive system – including the esophagus, gallbladder, large intestine (colon), small intestine, liver, pancreas, stomach, anus and rectum.

How is gastrointestinal cancer diagnosed?

When your physician suspects gastrointestinal cancer, he or she may recommend a series of diagnostic tests. These tests will vary depending on the symptoms presented. First, your doctor may order a physical exam and history. This will include an exam of the body to check general signs of health, including signs of disease, or anything that may seem unusual. He or she will also check a history of your health habits and past illnesses.

Your doctor may then order one or more of the following tests:

Complete blood count (CBC) - a procedure in which a sample of blood is drawn and checked for the following:

• The number of red blood cells, white blood cells and platelets.
• The amount of hemoglobin (protein that carries oxygen) in the red blood cells.
• The portion of the sample made up of red blood cells.

In a blood chemistry study, a blood sample is checked to measure the amounts of certain substances released in the blood by organs and tissues in the body. A higher or lower than normal amount of a substance can be a sign of disease. A tumor marker (a substance sometimes found in the blood, other body fluids, or tissue) may indicate a tumor in that area.

Upper endoscopy – a procedure to look inside the esophagus, stomach and duodenum (first part of the small intestine) to check for abnormal areas. An endoscope (a thin, lighted tube) is passed through the mouth and down the throat into the esophagus. To reduce pain and help you relax during the test, you may receive a pain medication and sedative through an intravenous (IV) line in your arm or hand.

Fecal occult blood test – a test to check stool (solid waste) for blood that can be seen only with a microscope.

Barium swallow – a series of x-rays of the esophagus and stomach. The patient drinks a liquid that contains barium (a silver-white metallic compound). The liquid coats the esophagus and stomach, and x-rays are taken. This procedure is also called an upper GI series.

Biopsy - the removal of cells or tissues so they can be viewed under a microscope to check for signs of cancer.

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.

Colonoscopy – the procedure examines the colon with a flexible, lighted tube called a colonoscope. A colonoscopy helps find ulcers, polyps, tumors, and areas of inflammation or bleeding. During a colonoscopy, tissue samples can be collected (biopsy) and abnormal growths can be taken out. A colonoscopy can also be used as a screening test to check for cancer or precancerous growths (polyps) in the colon or rectum.

Endoscopic ultrasound (EUS) – a special procedure for esophageal, rectal and anal cancer staging where doctors take images of the digestive tract and surrounding area.

Endoscopic Retrograde Cholangiopancreatography (ERCP) (en-doh-SKAH-pik REH-troh-grayd koh-LAN-jee-oh-PANG-kree-uh-TAH-gruh-fee) – ERCP is used primarily to diagnose and treat conditions of the bile ducts, including gallstones, inflammatory strictures (scars), leaks (from trauma and surgery), and cancer. ERCP combines the use of x-rays and an endoscope, which is a long, flexible, lighted tube.

Through the endoscope, the physician can see the inside of the stomach and duodenum (the first part of the small intestine), and inject dyes into the ducts in the biliary tree (the path by which bile is secreted by the liver on its way to the small intestine) and pancreas so they can be seen on x-rays.