Bowel cancer | Mate pukupuku i te whēkau

Also known as colon, rectal or colorectal cancer

Key points about bowel cancer

  • Bowel cancer (mate pukupuku i te whēkau) is any cancer that starts in the large bowel (colon) or rectum (back passage).
  • When detected early, it can be successfully treated.
  • The 3 main symptoms of bowel cancer are blood in your bowel motions (poo), an ongoing change in bowel habits and general abdominal discomfort (frequent gas, bloating or cramps).
  • Other symptoms include unexplained weight loss, tiredness and anaemia.
  • These symptoms can be caused by other conditions but it's important you get them checked out by your healthcare provider. 


Man clutching sore gut with eyes closed

Cancer occurs when cells within a certain part of the body divide and multiply too rapidly, producing a lump of tissue known as a tumour. In bowel cancer, this occurs in the colon or rectum. 

Bowel cancer often starts as small, non-cancerous polyps that form on the walls of the large intestine (bowel). Over time, some of these polyps may become cancerous.

If the polyps do become cancerous, the cancer cells can spread to the lymph nodes and bloodstream to other parts of the body, most commonly the liver and the lungs.

Risk factors for bowel cancer

Scientists are still unsure what causes cancer to develop in the bowel, but certain factors make you more likely to develop it, including:

  • Increasing age – in New Zealand 90% of people who develop bowel cancer are over the age of 50 years.
  • Family history of bowel cancer – especially if you have a close family member who has been diagnosed with bowel cancer at a young age (under 55 years)
  • Lifestyle factors, such as:
    • a diet high in red and processed meat, and low in fruit and vegetable fibre
    • smoking
    • drinking large amounts of alcohol
    • inactive lifestyle.
  • Having an inflammatory bowel condition, such as ulcerative colitis, for more than 10 years.
  • Having a rare inherited condition, known as polyposis that can lead to bowel cancer. Read more about polyposis(external link)(external link) from the NZ Familial GI Cancer Service.

The three main symptoms of bowel cancer are:

  • blood in your bowel motions – this may look like red blood or black bowel motions
  • a change in bowel habits that continues for several weeks, such as diarrhoea, constipation, or feeling that your bowel doesn't empty completely
  • general abdominal discomfort (frequent gas pains, bloating or cramps) that can be confused with indigestion. 

Other signs and symptoms include:

  • unexplained weight loss
  • tiredness
  • anaemia.

Although these symptoms are often caused by other conditions, it is important to check with a doctor without delay.

Take a look at the NHS Choices Bowel cancer symptom checker(external link)(external link) .

When you see your doctor, they will ask about your symptoms and whether you have a family history of bowel cancer. Your doctor may carry out some or all of the following tests and procedures to check for bowel cancer.

Rectal and abdominal examination

During this examination, your doctor inserts a gloved finger into the rectum to feel for any lumps, swelling or bleeding. Your doctor will also gently feel the surface of the abdomen to check for anything abnormal. These tests can be uncomfortable and many people find the rectal examination embarrassing; however, they take less than a minute to do.

Blood tests

  • A sample of your blood may be  taken to:
    count the number of red cells in your blood. A low level, anaemia, can be a sign of bowel cancer.
  • Look at a protein in the blood called carcinoembryonic antigen. This protein is sometimes raised in people with bowel cancer. However, it is not a reliable test to diagnose bowel cancer.

A test for blood in the bowel motions

The test used by the National Bowel Screening Programme is a faecal immunochemical test (FIT). It can detect tiny traces of blood present in a small sample of your bowel motion (poo). This may be an early warning sign that something is wrong with your bowel. A small amount of blood in your bowel motion can be caused by polyps (growths) or other minor conditions such as haemorrhoids (piles), which can easily be treated. Further investigation (usually a colonoscopy) is required to find the cause of bleeding.

Diagnostic tests

If your GP can confidently rule out other causes such as piles (following a rectal examination) and you are experiencing symptoms of concern, you should be referred to your local hospital for further investigations.


The doctor examines your rectum and the lower part of your bowel using a short tube (usually straight but may be flexible) called a sigmoidoscope. The doctor may also take a biopsy (a small sample of tissue).


The doctor or nurse inspects the entire length of your large bowel by gently inserting a long, flexible tube with a video camera in it called a colonoscope. This is passed through your anus and rectum into your colon. A sedative may be given before the colonoscopy.

Removing polyps at colonoscopy

If any polyps or other pre-cancerous lesions are found on the lining of your colon or rectum, your surgeon or gastroenterologist will remove them during the colonoscopy. A border of healthy tissue will also be removed. This is called a 'local resection'.

The polyps will be sent to a lab for analysis and if any cancer cells are found within them, your surgeon may decide you need a second, larger operation. This is to remove any cells that may have been left behind and to make sure that the cancer is unlikely to come back.

CT colonography (also known as virtual colonoscopy)

This X-ray technique is increasingly replacing barium enemas. The colon is emptied with a laxative. Air is then gently pumped into your bowel via your anus. CT scans are taken of your abdomen. If abnormalities are found, then this would usually lead on to a colonoscopy.

The three main treatments for bowel cancer are surgery, chemotherapy and radiation treatment. Most people will have surgery, while some people receive a combination of treatments. Monoclonal antibodies may also be used if the cancer has spread to other parts of the body.

Treatment choice depends on the size of the cancer, its location and whether it has spread. Your general health and your wishes are also important in the decision making. In some cases you may want to seek a second opinion.

If bowel cancer is detected early enough, there is a good chance it can be removed successfully and stopped from coming back. However, a complete cure is not always possible and the cancer may return. 

If the cancer has spread so far that it can not be removed completely by surgery, then a cure is very unlikely. In these cases, treatment focuses on controlling symptoms and slowing the spread of cancer.

Read more about treatment for bowel cancer below.

There are some factors that increase your risk of bowel cancer that you cannot change, such as family history and age. However, there are other factors to do with your lifestyle which you can change and by doing so reduce your chance of developing bowel cancer.

Lifestyle factors

There is strong evidence that certain lifestyle factors contribute to our risk of bowel and other cancers. To combat this, it is recommended that you:

  • adopt a healthy diet that includes:
    • less cured and processed meat, such as bacon, sausages and ham
    • less red meat and more fish
    • more fibre from cereals, beans, fruit and vegetables.
  • exercise regularly:
    • for adults, that’s at least 2.5 hours of moderate intensity activity every week. 
  • maintain a healthy weight:
  • quit smoking
  • cut back on alcohol

Read more about bowel cancer prevention(external link)(external link) from Bowel Cancer NZ.

Early detection

Bowel cancer is the second highest cause of death due to cancer in New Zealand. When detected early, it can be successfully treated.

Bowel screening cannot prevent bowel cancer, but it can help the condition be detected earlier. People who are diagnosed with bowel cancer and receive treatment at an early stage, have a 90% chance of long-term survival. If there is a delay in diagnosis and treatment, the cancer can become more advanced and harder to cure.

In New Zealand in 2011, a study was begun to see whether a bowel screening programme should be rolled out nationally. As a result of the successful pilot, from July 2017 a programme is being rolled out around the country, so that by 2020 bowel screening will be available to everyone aged 60 to 74 who is eligible for publicly funded healthcare in New Zealand. Read more about bowel cancer screening.

Information about the three main treatments for bowel cancer: surgery, chemotherapy and radiation treatment.

The three main treatments for bowel cancer are surgery, chemotherapy and radiation treatment. 

Surgery for bowel cancer

The type of operation you have will depend on:

  • where the cancer is in the bowel
  • the type and size of the cancer
  • whether the cancer has spread.

How long you stay in hospital will depend on the type of operation you have. Surgery to remove the part of the bowel which contains the cancer is called a colectomy. 

At the same time, 10 to 20 of the surrounding lymph nodes are removed so they can be examined under a microscope for signs the cancer has started to spread. At the end of surgery, the ends of the colon are joined back together. The place where they join is called an anastomosis.


Chemotherapy is the treatment of cancer using anti-cancer (cytotoxic) drugs. The aim is to destroy cancer cells while doing as little harm as possible to normal cells. Usually, treatment is given in cycles, spread over weeks or months. 

Chemotherapy is given by injection or drip into a vein, or via a portable infusion pump worn on the body to deliver the drugs continuously into the veins. Some chemotherapy drugs are given as tablets or capsules.

Chemotherapy is usually given as an outpatient (you do not need to stay in hospital).

Read more about chemotherapy

Radiation treatment

Radiation treatment is the use of high-energy radiation to destroy cancer cells or prevent them from reproducing. Radiation treatment only affects the part of the body at which the beam is aimed, so is very localised.

Radiation treatment is commonly used in rectal cancer. It is given most commonly before the operation to shrink the cancer so that the surgeon can remove it more easily. Less commonly, it is given after surgery to destroy any remaining cancer cells.

Radiation is usually given daily for five days a week. It can continue for 6–7 weeks, depending on the size of the tumour, the kind of treatment being used and the dose required. Blood tests and scans may be needed, and you will see your doctor once a week.

Read more about radiation treatment

Video series interviewing people about their personal journey with bowel cancer including the signs, symptoms and treatment.

Chelsea's story 

(Bowel Cancer, NZ, 2018)

Jonny's story

(Bowel Cancer, NZ, 2018)

For more personal stories of the same series visit Bowel Cancer NZ(external link)(external link)


Emotions and cancer English/Māori(external link) Cancer Society, NZ, 2020
Personal stories(external link)(external link) Bowel Cancer NZ
How we can help(external link)(external link) Cancer Society, NZ
NZ cancer services – find a hospital/service near you(external link)(external link) Healthpoint, NZ

Find out about the support available to you if you have bowel cancer.

There is a wide range of services and support for people and families living with cancer at all stages of the journey.

To find courses and support groups near you the Cancer Society of NZ(external link)(external link) cancer information helpline 0800 CANCER (226 237).

The helpline is staffed by nurses and provides a wide range of services from telephone support to booklets, pamphlets, DVDs and signposting to credible internet sites, including:

  • CanTalk – online magazine.
  • Information about services in your area.
  • The range of support groups, programmes, workshops, seminars and online forum available.
  • A range of supports from help with transport, accommodation to limited financial assistance during treatment.
Living well programme – Cancer Society

The living well programme(external link)(external link) is a free cancer information and support programme that offers practical ways of supporting people affected by cancer to build knowledge, self-confidence and self-help skills.

  • It is open to people with a cancer diagnosis, carers and whanau. 
  • Small groups are led by a trained facilitator and attendance is free.
Other people's experiences

To hear about other people who may have had a similar experience to you see the personal stories(external link)(external link) section on the Beat Bowel Cancer Aotearoa website. 

Learn more

About bowel cancer(external link)(external link) Beat Bowel Cancer Aotearoa, NZ
Brief information about bowel cancer(external link)(external link) Cancer Society, NZ

The content on this page will be of most use to clinicians, such as nurses, doctors, pharmacists, specialists and other healthcare providers.

Clinical guidelines and resources

Referral of patients with features suggestive of bowel cancer – Ministry of Health guidance(external link)(external link) BPAC, NZ, 2021
Surveillance for people with polyps or inflammatory bowel disease(external link)(external link) BPAC, NZ, 2021
Follow-up and surveillance for people after treatment for bowel cancer(external link)(external link) BPAC, NZ, 2021
Management of early colorectal cancer(external link)(external link) NZ Guidelines Group, Ministry of Health, NZ
Management of early colorectal cancer – pocket summary(external link)(external link) Ministry of Health, NZ, 2011
Colorectal cancer presenter slide set – oncology(zip, 5.5 MB)(external link)(external link) NZ Guidelines Group, Ministry of Health, NZ
Prioritising primary care patients with unexpected weight loss for cancer investigation – diagnostic accuracy study(external link)(external link) The BMJ, UK, 2020

(external link)

Resources for clinicians on the national bowel screening programme

Referral of patients with features suggestive of bowel cancer – Ministry of Health guidance(external link)(external link) BPAC, NZ, 2020
National bowel screening programme for health professionals(external link)(external link) National Screening Unit, NZ, 2017
Quick reference guide for primary healthcare teams(external link)(external link) National Screening Unit, NZ, 2018
National bowel screening programme(external link)(external link) Ministry of Health, NZ, 2017
Bowel screening pilot(external link)(external link) Ministry of Health, NZ, 2017
Bowel screening pilot – provisional results for the first screening round – January 2012 to December 2013(external link)(external link) Ministry of Health, NZ
Serious illness conversation guide Aotearoa(external link)(external link) Health Quality & Safety Commission, NZ, 2019
Blackmore T, et al. The characteristics and outcomes of patients with colorectal cancer in NZ, analysed by Cancer(external link)(external link) NZ Med J. 2020;133(1513):42-52.

Regional HealthPathways NZ

Access to the following regional pathways is localised for each region and access is limited to health providers. If you do not know the login details, contact your DHB or PHO for more information: 


Need help now?

Credits: Adapted from Cancer Society of NZ information by the Healthify editorial team

Reviewed by: Derek Luo, Counties Manukau DHB

Last reviewed:

Page last updated: