About Stomach Cancer

In this section you can find out more about:

This will help to give you a better understanding of the disease. Remember, if you want to know more or you have further questions, note them down and speak to your medical professional.

What is Stomach Cancer?

Stomach cancer usually develops over several years and affects the stomach and/or oesophagus. This is the tube that runs from your mouth to your stomach and because of this it is sometimes referred to as oesophagogastric cancer.

When you have stomach cancer the cells in the stomach or oesophagus become cancerous and begin to grow in an out-of-control fashion and eventually form a tumour. Although it is often referred to as stomach cancer, it can involve tumours that occur in the oesophagus.

Stomach Cancer

The stomach wall has five layers and these layers are central to defining the cancer stage (extent) and a patient’s prognosis. Stomach cancer often begins with cell changes in the innermost layer of the stomach wall (called the mucosa) which frequently go unnoticed. These pre-cancerous cells can develop into a tumour which may then spread beyond the inner layer of the stomach wall. Most stomach cancers start in the mucosa and this type of cancer is called adenocarcinoma.

When a cancer (also called tumour) extends from the mucosa into deeper layers of the stomach wall, the disease stage is more advanced and the prognosis is worse.


Tumours that start in different parts of the stomach may have different symptoms and outcomes. Tumour location has a large impact on which treatment is offered.

The spread or metastasis of stomach cancer varies. That is, a tumour can extend through the stomach wall and invade nearby organs. It may also spread via the lymphatic system to local lymph nodes. Stomach cancer can also spread through the bloodstream to other organs (e.g. bones, liver, lung). If stomach cancer does spread, then a patient’s prognosis is worse.

Who gets Stomach Cancer?

Stomach cancer is less common than some other forms of cancer and about 390 people will be diagnosed with the disease in New Zealand each year.1

It’s more common in men than in women and affects older people over the age of 60 more than younger people. Rates of stomach cancer are also higher in Māori and pacific Islanders.2 There are certain risk factors associated with stomach cancer. These include:

  • Exposure to the Helicobacter pylori bacteria, a common stomach infection. It’s thought the presence of this bacteria over a long period of time can potentially cause stomach cancer.
  • Having had Mucosa Associated Lympoid Tissue (MALT) lymphoma
  • Diet, particularly eating processed meats or smoked foods
  • Smoking
  • Obesity
  • Previous stomach surgery for non-cancerous conditions such as ulcers
  • A family history of stomach cancer.

These are general risk factors only and they do not necessarily mean that you will have stomach cancer. Check with your doctor if you have any concerns.