Bowel cancer is the second most common cancer in Aotearoa New Zealand.

What is bowel cancer?

Bowel cancer is cancer in any part of the large bowel, which includes the colon and rectum. It is sometimes called colorectal cancer.

Like the rest of your body, the bowel is made of tiny "building blocks" called cells.

Bowel cancer begins with the abnormal growth of these cells into lumps or tumours.

Cancer is a disease of the body's cells. It starts in our genes. Our bodies are constantly making new cells, a process controlled by certain genes. Cancers are caused by damage to these genes. As the damaged cells replicate a lump or tumour is formed. 

Tumours can be:

  • Benign - not cancerous. These do not spread to other parts of the body.
  • Malignant - cancerous


Depending on where it starts, it may be called cancer of the colon (large bowel) or cancer of the rectum (lower end of the large bowel).

Sometimes bowel cancer is also called colorectal cancer.

The bowel is a very important part of your body that helps you digest and absorb food and water. It extends from the stomach and stops at the anus. It is in two main parts – the small bowel (sometimes called the small intestine) and the large bowel (or large intestine). The large bowel is made up of the colon and the rectum.

The bowel is a tube made of a lining that absorbs food and water, which is surrounded by muscle to help squeeze the food along.

Food and liquid are broken down in the stomach. It is then digested in the small bowel before passing into the large bowel. Here water and some nutrients are absorbed, leaving waste.

Waste passes through the rest of the large bowel before leaving the body when you go to the toilet.


Whakaingoatia ai te matepukupuku puku hamuti e ai ki te wāhi kitea ai – hei tauira, matepukupuku o te kōpiro, matepukupuku o te tou rānei

Kīia ai te nuinga o ngā matepukupuku ki roto i te puku hamuti nui, ko te adenocarcinoma

Kāore e tino kitea ana te matepukupuku o te pukuhamuti iti

Kei roto i ngā tohu noa me ngā tohu mate o tematepukupuku puku hamuti, ko enei:

  • he toto kei roto i tō tiko (tērā pea, he rite ki te toto whero, he pango rānei te tiko)
  • ka rerekē te āhua o tō haere ki te tiko
  • korere, kōreke, te wā e kore tō puku hamuti e mahi tika
  • kua whāiti haere te tiko e puta ana i tō tou
  • ka auhi whānui te puku (te hia patero, te pupuhi o te puku, te kōpiropiro rānei)
  • te heke ohorere o tō taumaha
  • te hiamoe
  • anaemia

Ki te haere tonu ngā tohu mate puku hamuti mō te ono wiki nui ake rānei, me haere kia tirotirohia koe e tō rata.

Types of bowel cancer

Most bowel cancer is adenocarcinoma which starts in the gland cells of the lining of the bowel. 

Rarer types of bowel cancer include:

  • mucinous tumours
  • signet ring
  • squamous cell tumours
  • carcinoid tumours (neuroendocrine tumours)
  • sarcomas (mostly leiomyosarcomas)
  • lymphoma

Bowel cancer symptoms

Signs or symptoms of bowel cancer may include

  • Bleeding from your bottom or blood in your poo
  • A recent change in your bowel motions: going to the toilet more often, diarrhoea, constipation or a feeling that your bowel does not empty completely
  • tummy pain, bloating and cramps
  • weight loss for no reason
  • tiredness or weakness (fatigue)
  • low blood count (anaemia)

Early-stage bowel cancer often has no symptoms.

Having these symptoms does not mean you have bowel cancer, but it is important to get any changes checked by your doctor.

Tips for talking to your doctor

  • make a list of what you are feeling and how often it happens, including as much detail as possible
  • think about your family/whānau history of cancer and tell your doctor
  • go back to your doctor if you don't feel better, even if tests show you don't have a problem - you can ask for a second opinion if you want one 
  • take a family/whānau member or friend with you to the appointment for support

What causes bowel cancer?

Like many types of cancer, we don’t always know why people get bowel cancer, but some things increase your risk.

Risk factors for bowel cancer include:

  • Getting older, most cases are found in people over 50 years old
  • smoking tobacco
  • being overweight or obese
  • drinking alcohol
  • not exercising often 
  • having Crohn's disease or ulcerative colitis for more than 10 years
  • history of bowel cancer in your family/whānau
  • rare genetic conditions such as hereditary non-polyposis colorectal cancer (HNPCC) and familial adenomatous polyposis (FAP)

Having a parent, brother, sister or child who has had bowel cancer may increase your chances, but most cases of bowel cancer are not inherited. 

You cannot catch bowel cancer or pass it on through personal contact.

If you have a strong family history of bowel or other cancers, your doctor may recommend genetic testing through the Familial GI Cancer Service.

National Bowel Screening Programme

New Zealand has a free bowel screening programme available to those aged 60 to 74 years.

Time to screen

I Aotearoa nei, kua hōrapa tētahi hōtaka whakamātautau i te matepukupuku puku hamuti ki ia rohe, ki ia rohe, mō te hunga kāore e whai tohu mate ana. Mō te roanga ake o ngā kōrero, kōrero ki tō rata, me haere rānei ki te paetukutuku a te Manatū Hauora:

Need someone to talk to?
8:30 am to 5:00 pm Monday to Friday
0800 226 237 Information nurse

We know that going through cancer is tough and can raise many questions. You are not alone.

We have health professionals to answer your questions and provide the support you need. Get in touch

Last updated: August 2, 2023