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Stomach Cancer: Diagnosis

How is stomach cancer diagnosed?

If your healthcare provider thinks you might have stomach cancer, you’ll need certain exams and tests to be sure. Diagnosing stomach cancer starts with your healthcare provider asking you questions. You'll be asked about your health history, your symptoms, risk factors, and family history of disease. Your healthcare provider will also do a physical exam.

What tests might I need?

If signs are pointing to stomach cancer, you may have 1 or more of these tests:

  • Fecal occult blood test (FOBT)

  • Blood tests

  • Upper endoscopy

  • Upper GI series

  • Biopsy

Lab tests

Fecal occult blood test (FOBT)

This test is used to check for hidden blood in your stool. A small amount of your stool is put on a plastic slide or a special type of paper. You may do this test at home. Stomach cancer can sometimes cause small amounts of bleeding. This can be hard to see. But other problems that aren’t cancer can also cause it. Even if the test shows blood in your stool, you’ll likely need more tests to find the cause.

Blood tests

Blood tests can check if you have low red blood cell counts. This could be due to bleeding in your stomach. Blood tests can also be used to see how well certain organs are working and to get an idea of what your overall health is like. Tumor marker levels for CA19-9 and CEA may be checked. These markers are occasionally made by stomach cancer. And their levels may be higher at diagnosis.

Endoscopic tests

Upper endoscopy

This test is also called an EGD (esophagogastroduodenoscopy). It's a common procedure used to look for stomach cancer. It’s often the first test done.

This test lets your healthcare provider look at the inside of your stomach. A long, thin, flexible, lighted tube (endoscope) is used to do this. First, you are given medicines to make you sleepy. A numbing medicine is sprayed into your throat to help keep you from gagging. Then the scope is put in through your mouth and is passed down your food pipe (esophagus) and into your stomach. A camera on the end lets your provider look at your stomach lining. The provider also checks the lining of your esophagus and part of the first section of your small intestine (duodenum).

If your provider sees any abnormal changes in the tissue, small pieces (called samples) of the changed tissue can be taken out through the scope. They're then examined under a microscope for cancer cells by a pathologist. This is called an endoscopic biopsy. 

Imaging tests

Upper GI series

This is also called a barium swallow. It uses X-rays to find even small changes in your stomach lining. This test might be useful in some situations. It is used less often than an upper endoscopy since a biopsy can't be done during the test and it may miss some abnormal areas in the stomach. For this test, you’ll drink a thick, chalky fluid with barium in it. The barium lines your stomach. This makes it easier to see on an X-ray.

To look for very small tumors, your healthcare provider may use a double contrast method. For this, a small tube is placed in your stomach after you drink the barium. Air is then pumped through the tube into your stomach. The air makes the barium coating thinner around the inside of your stomach. This helps tiny changes in your stomach lining show up on the X-rays.


A biopsy is when your healthcare provider takes out small pieces of abnormal tissue from your stomach. A pathologist does tests on the tissue samples and looks at them under a microscope. It's the only way to know if a change is stomach cancer. But a biopsy can also show other problems. These can include an H. pylori bacterial infection, other diseases besides cancer, or another type of cancer called a lymphoma.

A biopsy is needed to confirm a diagnosis of stomach cancer.

Endoscopic stomach biopsy

This is the most common type of biopsy used. Before the procedure, you’re given medicine to help you relax and a numbing medicine is sprayed into your throat. It helps prevent gagging. Then your healthcare provider puts a long, thin, flexible tube called an endoscope into your mouth. It's guided down your esophagus and into your stomach. Your provider looks at the lining of your stomach with the scope. Tools can be passed through the scope to take tissue samples for a biopsy from any abnormal areas.

Endoscopic ultrasound-guided needle biopsy 

This procedure may be used if your healthcare provider thinks the cancer is deeper in the wall of your stomach (not just in the stomach lining).

This test also uses an endoscope. You’ll be given medicine to help you relax. A numbing medicine is sprayed into your throat to help prevent gagging. The endoscope is then put into your mouth and guided into your stomach. This scope has a special ultrasound tool at the tip. The ultrasound tip is put against your stomach wall to create images. 

Your healthcare provider looks at your stomach lining with the scope. They can also see images of the deeper layers of your stomach, lymph nodes, and other nearby tissues. If abnormal changes in the tissues are seen, your provider will pass a thin, hollow needle through the scope into the abnormal tissue. This needle is used to take out tiny pieces of tissue to test in the lab.

Getting your test results

Your healthcare provider will contact you with your biopsy results. Your provider will talk with you about other tests such as CT scans that you may need if stomach cancer is found. Make sure you understand the results and what follow-up you need.

Online Medical Reviewer: Jessica Gotwals RN BSN MPH
Online Medical Reviewer: Susan K. Dempsey-Walls APRN
Online Medical Reviewer: Todd Gersten MD
Date Last Reviewed: 8/1/2023
© 2024 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare provider's instructions.
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