Diagnosing stomach cancer

This page was reviewed under our medical and editorial policy by

Maurie Markman, MD, President, Medicine & Science

This page was updated on June 27, 2022.

A thorough and accurate stomach cancer (also known as gastric cancer) diagnosis is the first step in developing a stomach cancer treatment plan. Your team of stomach cancer experts will use a variety of tools and tests designed for diagnosing stomach cancer, evaluating the disease and developing your individualized treatment plan. Throughout your treatment, we'll use laboratory tests and imaging tools to monitor your response to treatment and modify your plan when needed.

Procedures for diagnosing stomach cancer 

Endoscopic procedures

These minimally invasive, outpatient endoscopic procedures allow a doctor to see inside the stomach. They include:

  • Esophagogastroduodenoscopy (EGD), also known as an upper endoscopy, is the primary test for diagnosing stomach cancer. To undergo an EGD procedure, you first receive a sedative. A gastroenterologist then inserts an endoscope (a thin, lighted tube) into your mouth. He or she passes the endoscope through your throat, down into your esophagus and stomach, and into the first part of your small intestine. The endoscope enables your gastroenterologist to see inside these organs to check for abnormalities, such as tumors, ulcers, obstructions and inflammation. He or she obtains biopsies of abnormal tissue through the endoscope. The tissue is then analyzed in the laboratory to look for signs of cancer. Although an endoscopy may help detect some types of stomach cancer, other types are harder to see and require additional testing to diagnose.
  • Endoscopic ultrasound (EUS) helps your gastroenterologist examine your stomach and organs, such as your pancreas, liver, gallbladder and bile duct. This test for stomach cancer uses sound waves to identify tumors and nearby lymph nodes to which the cancer may have spread. EUS allows your gastroenterologist to determine whether cancer has spread through multiple layers of your stomach, helping your doctors stage the disease and tailor your treatment plan.


If your doctor finds any unusual or suspicious areas during your upper endoscopy, an important diagnostic procedure called a biopsy is required to determine whether cancer cells are in the stomach. This procedure is the only way to know with certainty if cancer is present. In a biopsy, a small sample of cells is taken from a tumor and analyzed by a pathologist to determine if the cells are cancerous.

Tests for stomach cancer

There are many tests and exams that may be used to help detect, diagnose and stage stomach cancer. First, your doctor may gather your personal and family medical history and ask about any symptoms you’re experiencing, including:

  • Bloating
  • Pain
  • Issues with eating

Your doctor will also consider any risk factors that may make stomach cancer more likely.

Next, a physical exam may be conducted. Your doctor may feel your abdomen to detect any abnormalities.

Blood tests to measure your red blood cell count and fecal tests to check for blood in your stool may be ordered. Both of these factors may be affected by bleeding from stomach cancer.

If stomach cancer is suspected, your primary doctor will refer you to a gastroenterologist, a doctor with expertise in the digestive tract organs who may order additional testing.

Lab tests

Lab tests may be used to help diagnose stomach cancer. They include:

  • Advance genomic testing examines a tumor’s DNA to look for mutations or alterations that may be driving the growth of cancer. By identifying the mutations that occur in a cancer cell's genome, doctors may better understand what caused the tumor and tailor treatment based on these findings.
  • Complete blood count (CBC) tests determine the numbers of the different types of cells in the blood. A CBC blood test may help determine whether a patient has too few red blood cells, which causes anemia.
  • Liver function tests may be performed to assess the function of your liver, to which stomach cancer can spread.
  • Nutrition panel helps evaluate patients for deficiency of nutrients, such as vitamin D and iron. The test helps us identify the nutrients patients need replaced or boosted to support their quality of life.

Imaging tests

Imaging tests may be used to help diagnose and stage stomach cancer. They include:

  • Computed tomography (CT) scans are taken to reveal detailed images of your abdomen. The information obtained from CT scan images helps doctors detect cancer, determine its location in the stomach, and see whether it has spread to other abdominal organs.  
  • Magnetic resonance imaging (MRI) uses strong magnetic fields and radio waves to produce detailed images. These tests also allow for greater soft tissue contrast than a CT scan. This test isn’t used as often as a CT scan to detect stomach cancer, but it’s useful in helping to determine whether cancer has spread to other organs, such as the liver.
  • Positron emission tomography/computed tomography (PET/CT) scans help doctors detect stomach cancer, as well as determine the stage of the disease and whether it’s spread.
  • Ultrasound may be used if fluid is found in your abdomen. Ultrasound produces images of organs from high-energy sound waves and echoes to help your care team detect and stage stomach cancer. It may also be used to check for tumors that have spread to other organs.
  • Upper gastrointestinal series is a series of highlighted X-rays of the stomach, esophagus and the upper portion of the small intestine. This procedure requires the patient to swallow barium that enhances the X-ray images. If your doctor finds abnormalities during this procedure, the next step may be an endoscopic procedure or another diagnostic imaging test. These tests help in both detecting and staging stomach cancer.

Learn more about the stages of stomach cancer

Next topic: How is stomach cancer treated?

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Show references
  • American Cancer Society (2021, January 22). Tests for Stomach Cancer.
  • American Society of Hematology. Anemia.