If you have symptoms that could be a sign of gastric (stomach) cancer, see your GP as soon as possible.

Your GP will ask about your symptoms, including what they are, when you get them and whether anything you do makes them feel better or worse.

If your GP suspects you may have stomach cancer, they will refer you to a specialist for investigations. You will be referred within two weeks.

The main tests used to diagnose stomach cancer are outlined below.

An endoscopy is a procedure where a healthcare professional examines the inside of your stomach using a device known as an endoscope, which is a long, thin flexible tube with a light and a video camera at the end.

You will be awake for the endoscopy, but may be given a sedative by injection to make you feel drowsy and relaxed. You may also have a local anaesthetic sprayed onto the back of your throat, so the area is numbed.

The endoscope will then be passed down your throat and into your stomach so the specialist can look for any stomach ulcers or signs of cancer. If tissue is found that may be cancerous, your specialist will take a sample of it for testing. This procedure is known as a biopsy. The sample will be examined beneath a microscope in a laboratory. The results will show whether the cells are cancerous (malignant) or non-cancerous (benign), and normally take seven to 10 days to come back.

The endoscopy itself usually takes about 15 minutes, although you should allow about two hours for your visit.

After an endoscopy, you will not be able to drive for several hours, due to the sedative. You may also have a sore throat, although this should pass within a few days.

If you are diagnosed with stomach cancer, further tests may be needed to help determine how far it has spread and how quickly it is likely to spread (known as the stage and grade). Your cancer specialist will discuss this with you.

Computerised tomography (CT) or positron emission tomography (PET) scans take a series of X-ray images of your body. A computer then puts them together, creating a detailed picture of the inside of your body.

These scans will help your doctor assess how advanced your cancer is. It allows them to see whether the cancerous cells have formed tumours anywhere else in the body. The scan helps your doctors work out which type of treatment will be most effective and appropriate for you.

Your cancer specialist may decide you require a PET scan, but this procedure is not commonly used in diagnosing gastric cancer.

Your specialist may need to examine your stomach in more detail to see if the cancer has spread, especially to the lining of the abdominal cavity (peritoneum).

This procedure is carried out under a general anaesthetic, so you will be asleep.

Your specialist will insert a thin viewing tube with a camera on the end (a laparoscope) into your stomach through a small cut (incision) in the lower part of your tummy. In some cases, your specialist may need to examine more than one area of your stomach and may need to make more than one incision.

Sometimes biopsies are taken to examine specific areas of the abdomen such as the peritoneum or liver.

After all of the tests have been completed and your test results are known, it should be possible to tell what stage and grade of stomach cancer you have.

Staging is a measurement of how far cancer has spread. There are a number of different ways stomach cancer can be staged. One method uses a numbering system from one to four. The higher the number, the further the cancer has spread.

Some doctors may prefer to describe the stages of cancer using the more complex TNM staging system.

The three categories are used to create a more detailed classification:

  • T (tumour) – the location and size of the tumour
  • N (nodes) – whether the cancer has spread to the lymph nodes
  • M (metastatic) – whether the cancer has spread to other parts of the body such as the lungs, liver or bone

Cancer Research UK has more information about the staging and grading of stomach cancer.