Stomach cancer can be difficult to recognize as the initial symptoms are similar to those of less serious conditions. For this reason, stomach cancer is often only diagnosed once it has already reached an advanced stage.

An outline of the steps taken to diagnose stomach cancer are given below:

• A detailed patient history is obtained and a physical examination is performed. The doctor asks about any symptoms the patient has experienced as well as any family history of the condition. This is followed by a physical examination of the stomach to check for lumps and tenderness.
• If the doctor suspects stomach cancer, the patient is referred for specialist tests as well as blood tests and an X-ray to assess overall health.
• The main tests that are used to check for stomach cancer are described below:

Endoscopy – Here, a thin, flexible tube with a camera and a light source at its tip is passed down the esophagus and into the stomach so the inside of the stomach can be checked for evidence of cancer. If a lesion is spotted, a small tissue sample (biopsy) may be taken using an instrument attached to the tip of the endoscope.

Biopsy – The sample obtained from the lesion is observed under a microscope to check for cancer cells. As well as determining whether cancer is present, biopsy can reveal the type of cancer which may be adenocarcinoma (the most common cancer), carcinoid, gastrointestinal stromal tumor or lymphoma.

• Imaging studies – Examples of imaging studies that may be performed include, computed tomography (CT) scan and positron emission tomography (PET) scan. These techniques involve a series of X-rays which are then assembled with the help of a computer to provide detailed images of the inside of the body. These can be used to assess how advanced the cancer is, whether it has spread and which type of treatment may the most effective.

Stomach cancer staging

Stomach cancer can be divided into stages using the following numerical system:

• Stage 1A – The cancer remains within the inner lining of the stomach and has not spread to the lymph nodes.
• Stage 1B – Either a) the cancer is confined to the stomach lining but one or two lymph nodes are involved or b) the cancer has spread into the muscles but there is no lymph node involvement.
• Stage 2A – One of the following applies:

a) The cancer is confined to the stomach lining but has spread to three to six lymph nodes.
b) The cancer has invaded surrounding muscle as well as one or two lymph nodes.
c) The cancer has spread to the outer layer of the stomach but no lymph nodes are affected.

Stage 2B – One of the following applies:

a) The cancer is contained inside the lining but has spread to seven or more lymph nodes.
b) The cancer has spread to the muscles and has affected three to six lymph nodes.
c) The cancer has spread to the outer layer as well as one or two lymph nodes.
d) The cancer has spread outside the stomach but no lymph nodes are affected.

Stage 3A – One of the following applies:

a) The cancer has spread into surrounding muscles and involves seven or more lymph nodes.
b) The cancer has spread into the outer layer of the stomach and three to six lymph nodes are affected.
c) The cancer has spread outside of the stomach and to one or two lymph nodes.

Stage 3B – One of the following applies:

a) The cancer has spread into the outer layer of the stomach and seven or more lymph nodes.
b) The cancer has spread outside of the stomach and to three to six lymph nodes.
c) The cancer has spread beyond the outside of the stomach into surrounding tissue and also involves up to two lymph nodes.

• Stage 3C – The cancer has spread beyond the stomach into nearby tissues and organs as well as three or more lymph nodes.
• Stage 4 – The cancer has spread to other parts of the body such as the lungs and liver.