How is stomach cancer diagnosed and treated?

Stomach cancer cannot be diagnosed from the location of pain or a blood test alone. The diagnosis is usually made by examining the inside of the stomach during endoscopy and testing tissue taken from a suspicious area in a laboratory, after which the extent of the disease is assessed and the treatment sequence is chosen.

This sequence is not the same for everyone. Some early tumours can be treated with a local procedure, whereas cancer that has grown deeper into the stomach wall but has not spread to distant organs may require drug treatment before surgery. Starting treatment with medicines does not mean that surgery has been ruled out.

Which symptoms need attention?

There may be no symptoms in the early stages. Sometimes there is discomfort after eating, bloating, loss of appetite, nausea or a feeling of fullness after eating only a small amount. These symptoms also occur in other stomach conditions, so having one symptom does not amount to a cancer diagnosis, but symptoms that persist or differ from what you have experienced before are a reason to be examined.

Unexplained weight loss, increasing difficulty swallowing, repeated vomiting and persistent fatigue need prompt assessment. Small amounts of blood lost from the stomach over a long period can cause anaemia. Anaemia is a reduction in haemoglobin, which carries oxygen in the blood; a person may tire easily, become breathless and look pale. Taking iron alone without investigating the cause can leave the source of blood loss undetected.

Vomiting blood or material that looks like coffee grounds, black tarry stools, loss of consciousness or severe dizziness requires emergency medical care. Someone who is vomiting persistently and cannot even drink fluids should not wait for a scheduled appointment. These symptoms can have causes other than cancer, but they still require urgent assessment.

Helicobacter pylori and other risk factors

Helicobacter pylori is a bacterium that can live in the lining of the stomach. If it remains for a long time, it causes inflammation and, in some people, changes in the stomach lining that increase the risk of cancer. Finding the bacterium is not a cancer diagnosis. Most people with the infection do not develop stomach cancer, but appropriate treatment can reduce future risk.

Your doctor chooses the medicines to treat the infection. Previous antibiotic use and any drug allergies may affect this choice. An improvement in symptoms alone does not show that the bacterium has been cleared; a separate test is needed to check the result of treatment. Treating the bacterium does not replace investigation of ongoing symptoms such as weight loss or bleeding.

Smoking, frequently eating very salty or salt-preserved foods, a family history of stomach cancer and increasing age are also associated with risk. Thinning of the stomach lining as a result of long-standing inflammation is called atrophic gastritis. When these changes or certain inherited conditions are present, the need for follow-up is assessed individually. Knowing which relatives were affected and at what age is helpful to your doctor; having a relative with cancer does not mean that you will necessarily develop it.

What do endoscopy and biopsy show?

During endoscopy, a thin, flexible instrument with a camera is passed through the mouth to examine the oesophagus, stomach and beginning of the small intestine. A biopsy involves taking small tissue samples from a suspicious area during this examination. The doctor who examines the samples under a microscope determines whether the cells are cancerous and what type they are.

Because the endoscopic images and tissue results provide different information, the doctor assesses them together: endoscopy shows where the suspicious area is, while biopsy establishes the nature of the cells there. The first sample may not be sufficient. A repeat biopsy is then needed. A normal abdominal ultrasound or blood test does not rule out small changes in the stomach lining.

The tissue may also be tested for additional features. These features, called biomarkers, are proteins or genetic changes in the tumour cells; testing for them, particularly in advanced disease, helps determine whether another medicine should be added to the usual drug treatment. This is one reason why not every patient receives the same medicines.

How is the cancer stage determined?

The stage describes how deeply the tumour has grown into the stomach wall and whether it has spread to lymph nodes or distant organs. Lymph nodes are small tissue structures belonging to the body's immune system; cancer cells can spread to them. Knowing the size of the tumour alone is not enough to choose treatment.

Computed tomography, or CT, produces cross-sectional images of the body and helps assess the extent of spread. In some cases, endoscopic ultrasound to examine the stomach wall at close range, or an examination inside the abdomen using a camera through small incisions, is needed. The latter is called laparoscopy. Testing fluid taken from the abdominal cavity for cancer cells can also change the treatment plan.

Not everyone needs every test. When the results are reviewed by the surgeon, oncologist and other specialists, nutritional status and heart and lung conditions are also considered, because how well the body will tolerate the proposed treatment matters as much as the cancer stage.

Why is chemotherapy given before surgery?

Drug treatment intended to destroy cancer cells or slow their growth is called chemotherapy, and treatment given before surgery is described as neoadjuvant treatment. The aim is to shrink the tumour and also treat any cancer cells that may be present but are not visible on imaging. In suitable patients, drug treatment continues after surgery as well.

Not everyone receives the same treatment. A different approach may be chosen for very early disease; when cancer has spread to distant organs, medicines and measures to relieve symptoms may form the main treatment. During treatment, further tests assess the response, and the role of surgery is discussed again.

Information about the surgical stage is available on the laparoscopic surgery for stomach cancer page. An example of a procedure performed after chemotherapy can be seen in the surgery video; it contains surgical footage intended for adults. The sequence shown in the video relates to one particular case and does not determine another patient's treatment plan.