Stomach Cancer: Diagnosis

Approved by the Cancer.Net Editorial Board, 05/2016

ON THIS PAGE: You will find a list of common tests, procedures, and scans that doctors use to find the cause of a medical problem. To see other pages, use the menu.

Doctors use many tests to find, or diagnose, cancer. They also do tests to learn if cancer has spread to another part of the body from where it started. If this happens, it is called metastasis. For example, imaging tests can show if the cancer has spread. Imaging tests show pictures of the inside of the body. Doctors may also do tests to learn which treatments could work best.

For most types of cancer, a biopsy is the only sure way for the doctor to know whether an area of the body has cancer. In a biopsy, the doctor takes a small sample of tissue for testing in a laboratory. If a biopsy is not possible, the doctor may suggest other tests that will help make a diagnosis.

This list describes options for diagnosing this type of cancer, and not all tests listed will be used for every person. Your doctor may consider these factors when choosing a diagnostic test:

  • The type of cancer suspected

  • Your signs and symptoms

  • Your age and medical condition

  • The results of earlier medical tests

In addition to a physical examination, the following tests may be used to diagnose stomach cancer:

  • Biopsy. A biopsy is the removal of a small amount of tissue for examination under a microscope. Other tests can suggest that cancer is present, but only a biopsy can make a definite diagnosis. A pathologist then analyzes the sample(s). A pathologist is a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease.

  • Endoscopy. An endoscopy allows the doctor to see the inside of the body. The person may be sedated, and the doctor inserts a thin, lighted, flexible tube called a gastroscope or endoscope through the mouth, down the esophagus, and into the stomach and small bowel. Sedation is giving medication to become more relaxed, calm, or sleepy. The doctor can remove a sample of tissue as a biopsy during an endoscopy and check it for signs of cancer.

  • Endoscopic ultrasound. This test is similar to an endoscopy, but the gastroscope has a small ultrasound probe on the end that produces a detailed image of the stomach wall. An ultrasound uses sound waves to create a picture of the internal organs. The ultrasound image helps doctors determine how far the cancer has spread into the stomach and nearby lymph nodes, tissue, and organs, such as the liver or adrenal glands.

  • X-ray. An x-ray is a way to create a picture of the structures inside of the body using a small amount of radiation.

  • Barium swallow. In a barium swallow, a person swallows a liquid containing barium, and a series of x-rays are taken. Barium coats the lining of the esophagus, stomach, and intestines, so tumors or other abnormalities are easier to see on the x-ray.

  • Computed tomography (CT or CAT) scan. A CT scan creates a 3-dimensional picture of the inside of the body using x-rays taken from different angles. A computer then combines these images into a detailed, cross-sectional view that shows any abnormalities or tumors. A CT scan can also be used to measure the tumor’s size. Sometimes, a special dye called a contrast medium is given before the scan to provide better detail on the image. This dye is usually given both as a solution to swallow and into a vein.

  • Magnetic resonance imaging (MRI). An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. MRI can also be used to measure the tumor’s size. A special dye called a contrast medium is given before the scan to create a clearer picture. This dye is usually injected into a patient’s vein.

  • Positron emission tomography (PET) or PET-CT scan. A PET scan is usually combined with a CT scan (see above), called a PET-CT scan. However, you may hear your doctor refer to this procedure just as a PET scan. A PET scan is a way to create pictures of organs and tissues inside the body. A small amount of a radioactive sugar substance is injected into the patient’s body. This sugar substance is taken up by cells that use the most energy. Because cancer tends to use energy actively, it absorbs more of the radioactive substance. A scanner then detects this substance to produce images of the inside of the body.

  • Laparoscopy.  A laparoscopy is a minor surgery in which the surgeon inserts a scope into the abdominal cavity to evaluate spread of the stomach cancer to the lining of the abdominal cavity or liver. This pattern of cancer spread often cannot be seen on a CT or PET scan.

  • HER2 testing. Human epidermal growth receptor 2 (HER2) is a specialized protein found on the surface of cells. Many people are more familiar with HER2 when discussing breast cancer. However, doctors are finding that HER2 is also found in other types of cancer. When a cancer has abnormally high levels of HER2, it can drive its growth and spread. These types of cancer are referred to as HER2-positive. For HER2-positive cancers, certain types of targeted therapy may work well to treat these cancers. For patients diagnosed with gastroesophageal adenocarcinoma, ASCO, the American Society for Clinical Pathology (ASCP), and the College of American Pathologists (CAP) recommend HER2 testing to help guide treatment.

After diagnostic tests are done, your doctor will review all of the results with you. If the diagnosis is cancer, these results also help the doctor describe the cancer; this is called staging. 

The next section in this guide is Stages. It explains the system doctors use to describe the extent of the disease. Or, use the menu to choose another section to continue reading this guide.