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. Use the menu to see other pages.
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 if 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 section describes options for diagnosing stomach cancer. Not all tests listed below 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 general health
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.
- Molecular testing of the tumor. Your doctor may recommend running laboratory tests on a tumor sample to identify specific genes, proteins, and other factors unique to the tumor. Results of these tests can help determine your treatment options.
For stomach cancer, testing may be done for PD-L1 and high microsatellite instability (MSI-H), which may also be called a mismatch repair deficiency. The results of these tests help doctors find out if immunotherapy is a treatment option (see Types of Treatment).
- Endoscopy. An endoscopy allows the doctor to see the inside of the body with a thin, lighted, flexible tube called a gastroscope or endoscope. The person may be sedated as the tube is inserted 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. An ultrasound uses sound waves to create a picture of the internal organs. An ultrasound image of the stomach wall 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 takes pictures of the inside of the body using x-rays taken from different angles. A computer combines these pictures into a detailed, 3-dimensional image that shows any abnormalities or tumors. A CT scan can 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 liquid to swallow and an injection into a patient's vein.
- Magnetic resonance imaging (MRI). An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. MRI can 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 thin, lighted, flexible tube called a laparoscope into the abdominal cavity. It is used to find out if the cancer has spread to the lining of the abdominal cavity or liver. A CT or PET scan cannot often find cancer that has spread to these areas.
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. Use the menu to choose a different section to read in this guide.