Gastrointestinal Cancers

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Gastrointestinal Cancers

The gastrointestinal system is also known as your digestive system. The gastrointestinal system is made up of the digestive tract and organs that absorb and break down food into nutrients that the body needs. It also gets rid of waste products through the bowel.


Bowel cancer

The bowel is a part of the digestive system responsible for connecting the stomach to the rectum and facilitating the elimination of waste material (known as faeces or stool) from the body. The bowel is made up of the small intestine, large intestine, colon and rectum.

Bowel cancer develops from uncontrolled growth of abnormal cells within the colon or rectum. These cells may manifest as polyps, which have the potential to evolve into cancer with time. While polyps are prevalent and typically benign, not all instances of bowel cancer originate from them. Additionally, depending on the site of cancer initiation, it may be referred to as colon cancer, rectal cancer, or colorectal cancer.

The most common type of bowel cancer is adenocarcinoma (Source: Cancer Society NZ). Less common types of cancer affecting the bowel include lymphomas and neuroendocrine tumours.

Visit the Cancer Control Agency website for more information about the causes, symptoms, diagnosis and treatment of bowel cancer.


Gastrointestinal carcinoid tumours

A gastrointestinal carcinoid tumour is a cancer that forms in the lining of the gastrointestinal tract. The cancer starts from neuroendocrine cells, which make and release hormones. Gastrointestinal carcinoid tumours are also called neuroendocrine tumours.

Rangatahi impacted by a gastrointestinal cancer reflecting


Liver cancer

The liver is the largest organ in the body and is situated in the upper part of the abdomen on the right side of the body. The liver has many functions including clearing toxins from the body and producing bile to help digest food.

Primary liver cancer arises from the uncontrolled growth of abnormal cells within the liver. Without early detection and intervention, it can spread to other areas of the body. The types of primary liver cancer include:

  • Hepatocellular carcinoma (or hepatoma): this is the most common type of primary liver cancer. It starts in the main cells of the liver,
  • Cholangiocarcinoma (or bile duct cancer): this is a rare cancer that starts in the tissue of the bile duct, a tube that connects the liver and gallbladder to the bowel,
  • Angiosarcoma: a rare cancer that start starts in the blood vessels.

Secondary liver cancer, also known as metastatic cancer, originates from cancer that began in another organ and has subsequently spread to the liver. It is classified as cancer of the original site; for instance, if breast cancer spreads to the liver, it remains identified as breast cancer or metastatic breast cancer.

Visit the Cancer Control Agency website for more information about the causes, symptoms, diagnosis and treatment of liver cancer.


Oesophageal cancer

Oesophageal cancer starts in the oesophagus, the tube that connects your mouth to your stomach.

The main types of oesophageal cancers are adenocarcinoma (the most common) and squamous cell carcinoma.

Visit the Cancer Society website for more information about the causes, symptoms, diagnosis and treatment of oesophageal cancer.

Rangatahi impacted by cancer reflecting


Pancreatic cancer

The pancreas is part of your digestive system and sits behind your stomach. Its main function is to make digestive juices (enzymes) to break down the food you eat, and to make hormones, insulin and glucagon that control the level of sugar in your blood.

There are two main types of pancreatic cancer:

  • Pancreatic adenocarcinoma. Cancer starts in the cells that help to break down food (95% of all pancreatic cancers).
  • Pancreatic neuroendocrine cancer. Cancer starts in the cells that make hormones (5% of all pancreatic cancer) (Source: Cancer Society NZ).

Visit the Cancer Society website for more information about the causes, symptoms, diagnosis and treatment of pancreatic cancer.


Stomach Cancer

Stomach cancer, also known as gastric cancer, develops when abnormal cells in the stomach grow in an uncontrolled way.  The most common type of stomach cancer is called adenocarcinoma, which starts in the glandular cells of the stomach lining. It is also known as gastric cancer.

Visit the Cancer Society website for more information about the causes, symptoms, diagnosis and treatment of stomach cancer.


Other types of gastrointestinal cancers

Rarer types of gastrointestinal system cancers include anal cancer, small intestine cancer and gallbladder cancer.


Disclosure: The information provided in this article is intended for educational purposes only and should not be construed as medical advice.  Consult a qualified medical professional or your healthcare provider if you are seeking medical advice.



Discovering you, or a member of your whānau, is facing a gastrointestinal cancer can be really hard. A diagnosis of gastrointestinal cancer can result in a range of mixed reactions and life challenges.

Cancer affects everyone differently. That’s why Canteen provides a wide range of free support services to help rangatahi manage the specific challenges they’re dealing with. Canteen services and events can help you find ways to cope with what life looks like now you are facing these unexpected challenges.

You can talk to one of our specialist clinical team about the impacts of cancer on your life. This can be either in person, over the phone, or online. Rangatahi can also connect online 24/7 with peers who understand what you’re going through.

Alternatively, reach out to your Adolescent & Young Adult (AYA) key worker at the hospital for advice and support regarding a gastrointestinal cancer.

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Learn more about Canteen and the ways you can support rangatahi impacted by cancer.