If you have stomach cancer, you have a higher chance of being cured if your healthcare team detects it early. A CT scan is often part of the diagnosis.

Stomach cancer, or gastric cancer, happens when abnormal cells develop in your stomach, grow out of control, and form tumors.

Stomach cancer is a life threatening condition with a high chance of fatality, especially if the diagnosis comes during its late stages. The American Cancer Society (ACS) estimates that about 11,130 people will die of this condition in 2023.

A biopsy is the primary way to tell if you have stomach cancer. But tests like a CT scan help medical professionals make a proper diagnosis. In combination with a biopsy, a CT scan can help confirm the presence of stomach cancer, its location, and the extent of its spread.

Let’s discuss the role of CT scans in stomach cancer diagnoses, what happens during the procedure, other diagnostic tests for stomach cancer, and when to get medical attention.

Computed tomography (CT scan) uses X-rays to create detailed images of cross-sections of soft tissues in your body. Healthcare professionals can use a CT scan to find suspicious areas of the stomach that might have cancer cells.

According to a 2018 study, CT imaging is the most common way of diagnosing and staging gastric cancer.

CT scans can help confirm the location of stomach cancer, find out where it has spread, guide a biopsy needle to the specific area, and help determine the best treatment option for you.

Can a CT scan miss stomach cancer?

While a CT scan is helpful for identifying stomach cancer, there can be errors in the findings. Its accuracy in diagnosing stomach cancer will depend on factors like the cancer stage and the type of contrast used.

A 2020 study showed that CT scans are more likely to miss findings when cancer occurs in places like the mesentery (which attaches your intestine to the abdominal wall) and the peritoneum (which covers your abdominal organs, blood vessels, and liver).

Other tests to detect and diagnose stomach cancer include:

  • Blood tests: This includes measuring the number of white blood cells, red blood cells, platelets, and the amount of certain chemicals in the body. Blood tests can help find abnormalities that may lead to diagnosing stomach cancer.
  • Upper gastrointestinal endoscopy: Doctors commonly use endoscopy to diagnose stomach cancer. They use an instrument called an endoscope, which has a light and a lens. This lets them look into your stomach and check for abnormalities like ulcers, tumors, and bleeding.
  • Tumor marker tests: Tumor markers can be present in your tissues, blood, or other body fluids. When certain tumor markers like HER2 are present in abnormal amounts, it may mean you have stomach cancer.
  • Biopsy: Biopsy is the definitive test for diagnosing stomach cancer. It involves testing tissue samples from your body in a lab to determine if cancer cells are present.
  • Other imaging tests: Other imaging tests like PET scan, MRI, and chest X-ray may help detect stomach cancer. They use radiation, radioactive materials, magnets, or radiofrequency waves to create images of the scanned area.

Before the procedure

Your medical care team will let you know your specific instructions ahead of time. Typically, you will:

  • Avoid eating or drinking anything some hours before your appointment.
  • Wear loose, comfortable clothes, and remove jewelry or any metallic accessories.
  • A medical professional will inject you with a special dye called contrast, usually barium. This helps get clearer images.
  • Tell the healthcare team if you are allergic to any contrast dye, if you are pregnant, or have diabetes.

During the procedure

  1. Before the scan, you will get either an injection or intravenous (IV) infusion with a dye that will ensure a clear image.
  2. You’ll lie still on a table that passes into the CT machine.
  3. The table will slowly move through the scanner, and you may hear buzzing sounds.
  4. If your doctor suspects cancer has spread to an area, they may guide a biopsy needle into the suspected area during the scan to get a tissue sample for testing. If this is the case, you will also need anesthesia.
  5. The procedure may take 10–20 minutes.

After the procedure

A CT scan usually doesn’t cause side effects, and most people can go home soon after. However, because a contrast is often used for stomach scans, you may need to wait about an hour to be sure you don’t have a reaction.

You can expect your result within a few days or weeks.

Stomach cancer rarely causes symptoms in its early stages. But when symptoms are present, they may include:

Early symptoms of stomach cancer

Later symptoms of stomach cancer

If you think you might have stomach cancer or are worried about symptoms, consider speaking with a doctor. Showing symptoms may not mean you have stomach cancer, but a proper diagnosis will rule that out with certainty and possibly show the underlying cause.

Here are answers to some commonly asked questions about stomach cancer diagnosis.

How can you identify stomach cancer early?

There is no standard test for detecting stomach cancer early in the general population. But if your healthcare team suspects you have stomach cancer, they can run tests, including physical examinations, upper endoscopy, scans, and biopsies.

How accurate is CT for stomach cancer?

A CT scan has up to 90% accuracy for diagnosing stomach cancer, particularly when multiplanar reconstruction or reformation (MPR) is used to reconstruct the images.

Can abdominal ultrasound identify stomach cancer?

Yes, abdominal ultrasound can help detect and stage stomach cancer. It can also help determine if tumors have spread to nearby organs.

What is the best scan for stomach cancer?

Your healthcare team will determine your condition’s best diagnostic approach, including imaging tests. MRIs, CT scans, and PET scans can all be useful for detecting and staging stomach cancer.

Stomach cancer is often identified in later stages because it rarely causes early symptoms. However, survival rates are higher if identified in the early stages. Your doctor may need a CT scan to diagnose your condition if they suspect stomach cancer. A CT scan is considered safe and effective.