Diagnostic tests are needed to determine whether symptoms are, in fact, stomach cancer. If cancer is found, additional tests may be used to assess the stage of the disease, specifically, how advanced the cancer is, and whether it has metastasized (spread outside the stomach).

Diagnostic tests may include:

• Physical exam and history 
• Gastroscopy A thin, lighted tube called a gastroscope is inserted through the mouth and guided into the stomach. A local anesthetic or other medicine may be given to minimize discomfort.
• Barium swallow/Upper GI series A series of X-rays is taken after the patient drinks a liquid to improve the visualization of the inside of the upper gastrointestinal tract.
• Biopsy If tests indicate that stomach tissue seems abnormal, a small sample may be taken for examination under a microscope to check for cancer cells. This is called a biopsy.