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Stomach Cancer

What is the Stomach?

The stomach is part of the digestive system. The stomach is a hollow muscular tube, with a sphincter (valve) at each end and is located on the upper left side of your abdomen. The stomach is a muscular sack-like organ that receives and stores food from the oesophagus. With the help of gastric juices that are released from glands in the inner lining of the stomach, the stomach breaks down food into a thick liquid. Once the food is broken down, it is passed from the stomach to the small bowel, where nutrients are absorbed into the bloodstream.

Parts of the stomach

  • Cardia: The first part is closest to the oesophagus
  • Fundus: The upper part of the stomach
  • Body: The main part of the stomach
  • Antrum: The lower portion (near the intestine), where the food mixes with gastric juice
  • Pylorus: The last part of the stomach, which acts as a valve to control emptying of the stomach contents into the small intestine

What is Stomach Cancer?

Also known as gastric cancer, there are several different types of stomach cancer:

  • Adenocarcinomas: about 95% of stomach cancers develop in the cells that line the inside surface of the stomach and are called gastric adenocarcinomas.
  • Lymphomas: cancer of specialised cells that are part of the immune system. These can arise in the stomach or other parts of the digestive tract.
  • Gastro-Intestinal Stromal Tumours (GISTs): cancer arising from pacemaker cells that control stomach wall muscle contractions. GISTs can also develop in other parts of the digestive tract but most frequently occur in the stomach.
  • Carcinoid tumours (also known as neuroendocrine tumours or NETs): cancer of hormone-producing cells. These can arise in the stomach as well as in other parts of the digestive tract.

Stomach Cancer in New Zealand

The main form of stomach cancer (adenocarcinomas) can be split into two sub-types; intestinal and the less common diffuse-type. Stomach cancer in New Zealand has some of the largest inequities for our Māori and Pasifika populations who are 3 times more likely to develop the disease than NZ Europeans. This inequity is linked to two main factors:

  1. Intestinal­-type stomach cancer is linked to a number of environmental factors that Māori and Pasifika communities are more exposed to such as; Helicobacter pylori (H. pylori) infection, smoking and salt-preserved foods. More details about the risk factors associated with stomach cancer can be found below.
  2. Diffuse-type stomach cancer is linked to hereditary gene mutations, such as the CDH1 mutation, which are far more prevalent in Māori whānau.

Read our opinion piece about stomach cancer in New Zealand

Hereditary diffuse-type stomach cancer

Hereditary stomach cancer is cancer that is caused by a mutation in a particular gene that is passed down through family and whānau. This type of hereditary mutation usually causes diffuse-type stomach cancer. The level of hereditary diffuse-type stomach cancer in New Zealand is much higher than in many other countries. There has been excellent research led by Professor Parry Guilford (Te Aho Matatū), Associate Professor Karyn Paringatai and driven by Maybelle McLeod (Kimihauora Health and Research Clinic) into the CDH1 gene mutation and its impact on whānau and how understanding whakapapa can help identify those most at risk.

The prevalence of the CDH1 gene among some Māori whānau accounts for between 20-50% of these cases, but the cause of the rest remains unknown. This means New Zealand has unique epidemiology around stomach cancer that needs to be researched further to ensure we can identify those New Zealanders at most risk and are giving New Zealanders appropriate treatment options.

Treatment and Diagnosis


Stomach cancer is usually diagnosed by blood tests and an endoscopy, where a flexible tube with a camera on the end is passed down from the mouth, and samples of tissue, called biopsies, are taken and sent to the lab for testing. Other tests used to help with the diagnosis include barium x-rays, MRI, and CT scans.

For a full list of diagnostic tools and more detail visit the Pancare website.


The treatment of stomach cancer depends on its site within the stomach, the stage of the cancer (how advanced it is at the time of diagnosis), the type of cancer, and whether the person is otherwise medically fit. Surgery to remove part or all of the stomach is the most common treatment, but radiotherapy and chemotherapy may also be used. These treatments are sometimes used in combination. The prognosis after treatment depends on the stage and the treatment given. In the best circumstances, cure is possible. If cure is not possible, the symptoms caused by the cancer can often be alleviated.

For more details about the treatment options for stomach cancer visit the Pancare Foundation website.

Side Effects from Treatment

As with any medical treatment, you may experience side effects from your stomach cancer treatment. It is important to talk to your doctor about any potential side effects that are worrying you.

Cancer treatments such as chemotherapy, kill cancer cells, but in the process, they damage normal healthy cells and cause side effects. These side effects vary from person to person and depend on the type of treatment, the part of the body treated, and the length and dose of treatment.

Most side effects are temporary and go away after treatment ends. Learn how to control and manage these side effects to improve your daily wellbeing.
Side effects could include:

  • Fatigue
  • Pain
  • Diarrhoea and malabsorption
  • Weight loss
  • Loss of appetite
  • Feeling full quickly

Chemotherapy and biological therapies

  • Nausea and vomiting
  • Loss of appetite
  • Fatigue
  • Weight loss
  • Sore mouth or throat
  • Taste changes
  • Foggy brain

Radiation therapy

  • Pain and burning sensation
  • Fatigue
  • Weight loss

For detailed information on potential side effects and how to manage them, visit the Pancare Foundation website.

Diet and Nutrition

Stomach cancer itself and cancer treatment place extra demands on your body. It is very important to maintain good nutrition before, during, and after cancer treatment. Treatments may involve surgery, chemotherapy, radiotherapy, immunotherapy, or a combination of these. These treatments can cause you to lose your appetite and energy, putting you at an increased risk for malnutrition.

Your food choices when you have cancer and are undergoing treatment may be very different from what you are used to eating. The main goal is to try to keep your weight constant, maintain muscle strength, maintain a healthy weight, and have more energy, all of which help your body to heal properly, improve your quality of life and give you the energy to cope with all the new challenges treatment may bring.

The role of the stomach and the digestive system

The stomach is part of the digestive system. The stomach is a hollow muscular tube, with a sphincter (valve) at each end and is located on the upper left side of your abdomen. Its function is to store food while it is being mixed with stomach enzymes that breaks and secrete a strong acid that kills any bacteria that entered with the food or drink. When the contents of the stomach are processed enough, they are released into the small intestine. Any disease or treatment targeting the stomach can affect digestion.

For detailed information on the role of nutrition, tips on how to maintain good nutrition during treatment, and the impact of treatment and surgery, visit the Pancare Foundation website.

Symptoms and Risk Factors


The symptoms of stomach cancer are often vague and non-specific. They are often subtle and occur in other medical conditions apart from stomach cancer, making them difficult to link to stomach cancer. Stomach cancer symptoms vary widely and include:

  • a painful or burning sensation in the abdomen
  • heartburn or indigestion (dyspepsia)
  • a sense of fullness, even after a small meal
  • nausea and/or vomiting
  • loss of appetite and/or weight loss
  • swelling of the abdomen
  • unexplained tiredness or weakness
  • low iron levels, red blood count/ anemia
  • blood in vomit
  • black-coloured stool

It is best to see your doctor for review and investigation if you experience unexplained symptoms that worry you. They will ask you questions to help understand whether the cause of symptoms are stomach cancer or another condition.

Risk Factors

Risk factors for stomach cancer some elements that are environmental and others that cannot be controlled i.e.:

Age: Stomach cancer can occur in younger people, but the risk goes up as a person gets older. Most people diagnosed with stomach cancer are in their 60s, 70s, or 80s. (However, people with a family history, in particular Māori, can be impacted at a much younger age).
Gender: Stomach cancer is more common in men than in women.
Ethnicity: Māori & Pacific Island communities are at higher risk of stomach cancer than NZ Europeans.
Societal and environmental factors that increase the risk of stomach cancer include:
Helicobacter pylori infection: Infection with Helicobacter pylori (H pylori) bacteria seems to be a major cause of stomach cancer, especially cancers in the lower (distal) part of the stomach. Long-term infection of the stomach with this germ may lead to atrophic gastritis and other pre-cancerous changes of the inner lining of the stomach.
People with stomach cancer have a higher rate of H pylori infection than people without this cancer. H pylori infection is also linked to some types of lymphoma of the stomach. Even so, most people who carry this germ in their stomach never develop cancer.
Being overweight or obese: Being overweight or obese is linked with an increased risk of cancers of the cardia (the upper part of the stomach near the esophagus).
Diet: Stomach cancer risk is increased in people whose diets include large amounts of foods preserved by salting, such as salted fish and meat and pickled vegetables. Eating processed, grilled, or charcoaled meats regularly appears to increase risk of non-cardia stomach cancers.  Eating few or no fruits likely increases the risk of stomach cancer.  On the other hand, eating lots of fresh fruits (especially citrus fruits) and raw vegetables appears to lower the risk of stomach cancer.
Alcohol use: Alcohol use probably increases the risk of stomach cancer. The evidence for this link is strongest for people who have 3 or more drinks per day.
Tobacco use: Smoking increases stomach cancer risk, particularly for cancers of the upper part of the stomach near the esophagus. The rate of stomach cancer is about doubled in people who smoke.

Statistics and Useful Resources

NZ Statistics

More than 400 people in New Zealand are diagnosed with stomach cancer each year. This includes a small number of people with gastro-intestinal stromal tumours (GIST) and neuroendocrine tumours (NETs). NETs are found in the stomach but can appear elsewhere in the digestive system.

Overall 5-year survival rates for stomach cancer are around 29% and around 280 New Zealanders die from stomach cancer each year.
Stomach cancer is one of the cancers with the greatest inequeties for Māori when compared with non-Māori. Māori are 3 x more likely to develop stomach cancer than NZ European communities and are over 3.5x more likely to die from the disease.

Useful Websites

PanCare Foundation

Unicorn Foundation (neuroendocrine tumours)

Cancer Council (Australia)

Personal Stories