How Is Gastric Cancer Diagnosed?

If you have some of the symptoms of gastric cancer, your doctor will begin your diagnosis with a medical history and physical examination.

• Medical history and physical examination - Your doctor will take a complete medical history by asking you about your risk factors, symptoms, and other health problems or concerns. The doctor will also do a physical exam to look for signs of gastric cancer and other health problems. Your doctor will pay special attention to your abdomen (area between your chest and your hips) to see if it is swollen or changed in any way.

The doctor may use upper endoscopy to diagnose gastric cancer. He or she will take a biopsy (remove tissue for examination) of any tissue that looks abnormal.

• Upper endoscopy (gastroscopy) - An endoscope (or gastroscope) is a thick, flexible, lighted tube attached to a small camera. During an upper endoscopy, the doctor passes an endoscope down your throat and uses the instrument to see the lining of your esophagus and stomach. If the doctor sees any abnormal areas, he or she can remove tissue samples using instruments passed through the endoscope.

If your doctor sees something suspicious in your stomach, he or she will perform a biopsy. A biopsy is the only way to be sure whether you have gastric cancer.

• Biopsy - A biopsy involves cutting out a small piece of tissue and sending it to a laboratory. A pathologist (doctor who specializes in diagnosing diseases) will look at the tissue under a microscope to see whether it has cancer cells. The doctor might use upper endoscopy, computed tomography scanning, or endoscopic ultrasound (see below) to help guide the biopsy needle.

Certain laboratory tests can be helpful in figuring out how serious (advanced) the gastric cancer is.

• Complete blood count - This blood test is used to measure hemoglobin (protein in red blood cells that carries oxygen), hematocrit (balance between red blood cells and plasma), white blood cells (which fight infection), and platelets (which help clot blood) in your blood. This test is useful for finding out whether you have anemia (too few red blood cells), which could be a sign of internal bleeding and possibly of gastric cancer.
• Fecal occult blood test (FOBT) - This test is used to find out whether any blood is hidden (occult) in your stools. If the test shows that your stools have blood, this could be a sign of gastric cancer.

Imaging procedures allow doctors to learn where the cancer is located and whether it has spread from the original bone to other areas of the body. This can help determine which treatments will work best.

• Chest x-ray - A chest x-ray is used to find cancer that has spread (metastasized) to the lung or to find out if you have any serious lung or heart diseases that might be affected by treatment of your cancer.
• Computed tomography (CT or CAT) scan - Instead of taking one picture, like a conventional x-ray, a CT scanner takes many pictures as it rotates around you. A computer combines these pictures into an image of a slice of your body (like a loaf of sliced bread). A CT scan can show where the cancer is located and whether the cancer has spread to organs or lymph nodes near or outside the stomach. This information is useful for identifying the cancer stage and whether the cancer can be treated successfully with surgery. CT scans are sometimes used to guide a biopsy needle into an area that might be cancerous (CT-guided needle biopsy). 
• Endoscopic ultrasound (EUS, endosonography) - The doctor puts a small ultrasound probe (transducer) onto the tip of an endoscope and passes the endoscope down your throat and into your stomach. The transducer sends out sound waves and a computer uses their echoes to produce a picture of structures inside your body. EUS is useful for finding out how far the cancer has spread into the stomach wall and whether it has traveled to lymph nodes or other parts of the body. It can also be used to guide a needle to collect a tissue sample (EUS-guided needle biopsy).
• Laparoscopy - A laparoscope is a thin, flexible tube with a small camera on the end. During laparoscopy, the doctor inserts a laparoscope through a small opening made through minor surgery in your side. The laparoscope’s camera sends pictures of the inside of your abdomen to a TV monitor. These images show the surfaces of different organs and nearby lymph nodes. Laparoscopy is useful for staging gastric cancer. It can also be combined with ultrasound to improve the accuracy of the diagnosis.
• Magnetic resonance imaging (MRI) - This procedure uses powerful magnets and radio waves to take detailed cross-sectional images. MRI produces images of cross-sectional slices of your body like a CT scanner. It can also make images of slices that are parallel to the length of your body. MRI is useful in finding out whether the cancer has spread beyond the stomach.
• Positron emission tomography (PET) scan - Cancer cells use more glucose (sugar) than most other body organs. During a PET scan, the doctor injects a small amount of glucose containing a radioactive substance into your arm. A special camera in the PET machine can detect the radioactivity. This test is useful to see if the cancer has spread beyond the stomach, which might mean that it cannot be removed with surgery. PET scans are also used to stage gastric cancer.
• PET/CT scan - Sometimes, CT scans and PET scans are combined to find cancer that has spread from the stomach into other parts of the body. The combined test can also be used to stage the cancer.
• Upper gastrointestinal (GI) series (barium swallow, barium upper GI series, barium x-ray, stomach x-ray) - Before having this series of x-rays, you will drink a liquid that contains barium. The barium coats the lining of the esophagus, stomach, and intestines and makes tumors and other abnormalities show up more clearly on the x-rays. You will then have several x-rays taken. These x-rays are helpful in ruling out gastric cancer—if the x-rays do not show any cancer, then you almost certainly do not have this disease. However, if the x-rays show that you might have cancer, you will need more tests.

This content has been reviewed and approved by Myo Thant, MD.