Brief information about bowel cancer

This information has been prepared to provide you with information about cancer of the bowel.

Bowel cancer is named according to where in the bowel it is found: for example, cancer of the colon or cancer of the rectum. This cancer occurs when the cells in some part of the bowel grow abnormally and form a lump or tumour. Most cancers are in the large bowel (see diagram below). Cancer in the small bowel is very rare and is not discussed in this information sheet.

I whakaritea tēnei puka hei whakarato pārongo mō te matepukupuku o te puku hamuti nui (kōpiro) me te tou. Mehemea kua pā te matepukupuku ki tō puku hamuti iti (ileum), ka whakataunaki mātou kia pānuitia e koe te rauemi ā-ipurangi a . Ka puta te matepukupuku puku hamuti nui i ngā wā e tino rerekē ana te tipu o ngā pūtau, ā, ka puta he puku. Kitea ai te nuinga o ngā matepukupuku puku hamuti i roto i te kōpiro.

How common is bowel cancer?

 Bowel cancer is the second most common cancer in New Zealand. 93 per cent of cases are found in people over
the age of 50.

Diagram showing the large bowel


Common signs and symptoms of bowel cancer may include:

  • blood in your bowel motions (this may look like red blood or black bowel motions)
  • a change in bowel habits
  • diarrhoea, constipation or feeling that your bowel doesn’t empty completely
  • bowel motions that are narrower than usual
  • general abdominal discomfort (frequent gas pains, bloating or cramps) that can be confused with indigestion
  • unexplained weight loss
  • tiredness
  • anaemia.

Although symptoms are often caused by other conditions, it is important to get them checked by your doctor without delay

When you’re diagnosed with bowel cancer, you may also be concerned about your family’s risk of bowel cancer. While your family may not be at increased risk, you may wish to discuss with them the importance of reporting symptoms to their doctor early.

Screening for bowel cancer

A bowel cancer screening programme is being rolled out throughout New Zealand. People between the ages of 60 – 74 years of age without any symptoms of bowel cancer are eligible to join the programme. For more information, talk to your doctor or visit the Ministry of Health’s website:


A number of tests can be performed to diagnose bowel cancer. You may have some or all of the following tests:

Rectal examination

The doctor inserts a gloved finger into your rectum (back passage) to check for any lumps, swelling or bleeding.

Abdominal examination

The doctor will gently feel the surface of your abdomen to check for any lumps.

Blood count

A sample of your blood is taken to count the number of red cells in your blood (a low level (anaemia) can be a sign of bowel cancer).

Carcinoembryonic antigen (CEA)

CEA is a blood test that looks at a protein in the blood. It 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

A sample of your bowel motion is checked for blood.

Barium enema

The barium shows up on the X-rays and gives a clear picture of your bowel

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 (back passage). CT scans are taken of your abdomen. If abnormalities are found then this would usually lead onto a colonoscopy.


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.


CT (computerised tomography) scans are undertaken, in most patients with bowel cancer to see if the cancer has spread to other parts of the body. MRI scans are done to help the surgeon plan some operations, particularly for rectal cancer. Occasionally PET (positron emission tomography) scans are used if a CT or MRI scan is unclear, but most patients do not need this test.


In most cases there are a number of ways of treating bowel cancer.

These treatments include:

  • surgery
  • chemotherapy
  • radiation treatment
  • monoclonal antibodies.

Most people will have surgery. Some people receive a combination of two or more treatments. The treatment depends upon the size of the cancer, where it is and whether it has spread. Your general health and your wishes are also important in the decision making.


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
  • Your general health and your wishes
    are also important in the decision making.

How long you stay in hospital will depend on the type of operation you have.

Staging the bowel cancer—to see how far it has spread

After the operation, the laboratory will examine the cancer and surrounding tissue to assess the stage (size and extent) of the cancer, and whether it has spread to the lymph nodes or other organs, such as the liver.

With this information, the doctor will decide if further treatment is recommended. This can be an anxious time as it may take up to 10 days for the results to come back.


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. Some chemotherapy drugs are given as tablets or capsules.

Other chemotherapy drugs are given by injection or drip into a vein, usually in your arm or hand, or via a portable infusion pump worn on the body to deliver the drugs continuously into your bloodstream. Chemotherapy is usually given as an outpatient.

For more information, ask for the booklet at your local Cancer Society or call the Cancer Information Helpline 0800 CANCER (226 237) for a copy.

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(s) is aimed, so is 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 six to seven weeks, depending on the size of your cancer, 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.

For more information, ask for the booklet Radiation Treatment/Haumanu Iraruke at your local Cancer Society or phone the Cancer Information Helpline 0800 CANCER (226 237) for a copy.

Chemo-radiation (chemotherapy and radiation treatment together)

Radiation treatment can be given in combination with chemotherapy to treat:

  • cancer that has spread to areas close to the rectum (locally advanced rectal cancer) before surgery, to try to shrink the cancer and make surgery easier
  • cancer that has spread to other distant parts of the body (metastatic cancer) to shrink the cancer and control symptoms such as pain and bleeding.
  • It may also be given with oral chemotherapy after surgery for rectal cancer to reduce the chances of your cancer coming back but this is less common.


Making decisions about treatment

If you are given a choice of treatments, including no treatment for now, you will need to think about your options. You may want to ask your doctor questions such as:
  • what is the goal of the treatment?
  • can I expect to live longer if I have treatment?
  •  if I have treatment, is there a risk that my quality of life will be affected by the treatment?
  •  are there other treatments for me?
  • what is the chance of the treatment working?

Before you see your doctor, it may help to write down any questions you would like answered. We suggest that you take someone with you to your appointments to support you to get the information that you need.

Talking with doctors

You may want to see your doctor a few times before making a final decision on treatment. It is often difficult to take everything in, and you may need to ask the same questions more than once. You always have the right to find out what a suggested treatment means for you, and the right to accept or refuse it.

A second opinion

You may want to ask for a second opinion from another specialist. Your specialist or general practitioner can refer you to another specialist and you can ask for your records to be sent to the second doctor. You may be interested in looking for information about bowel cancer on the internet. While there are very good websites, some websites provide wrong or biased information. We recommend you begin with the Cancer Society’s site and use our links to other good cancer websites. See the end of this Information Sheet for a list of recommended websites.

Taking part in a clinical trial

Research into the causes of bowel cancer and ways to prevent, detect and treat it is ongoing. Your doctor may suggest that you consider taking part in a clinical trial. You could also ask if there is a clinical trial for your particular kind of cancer.

After treatment

During your illness you will be monitored frequently. This usually involves regular CEA blood tests and colonoscopy. After the completion of your treatment, you will need to have regular check-ups. Your doctor will decide how often you will need these check-ups as everyone is different. Check-ups will gradually become less frequent if you have no further problems.


Emotional support

People react in different ways when they learn they have bowel cancer. Feelings can be muddled and change quickly. This is quite understandable and there is no right or wrong way to feel.

It may be helpful to talk about your feelings with someone you are close to. The Cancer Society has a telephone support service, Cancer Connect, where we can link you to someone who has had bowel cancer. For more information, phone the Cancer Information Helpline 0800 CANCER (226 237).

Your local Cancer Society can provide information and support. The Cancer Information Service is a Cancer Society service where you can talk about your concerns and needs with specially trained nurses.

Call your local Cancer Society and speak to support services staff or phone the Cancer Information Helpline 0800 CANCER (226 237).

Local Cancer Society centres offer a range of services for people with cancer and their families. These may include:

  • volunteer drivers providing transport to treatment
  • accommodation while you’re having treatment
  • support and education groups.

The range of services offered differs in each region, so contact your local centre to find out what is available in your area.

What can I do to help myself?

Many people feel that there is nothing they can do when they are told they have cancer. They feel out of control and helpless for a while. However, there are practical ways you can help yourself.

Diet and food safety

A balanced, nutritious diet will help to keep you well and able to cope with any side effects of treatment. The Cancer Society’s booklet Eating Well/Kia Pai te Kai provides useful advice about eating well during treatment. Phone your local Cancer Society office or call the Cancer Information Helpline 0800 CANCER (226 237).


Research has indicated that people who keep active cope better with their treatment. Discuss with your doctor what exercise is best for you.

Relaxation techniques

Some people find relaxation or meditation may help them feel better. The hospital social worker, nurse or your local Cancer Society may know whether the hospital runs any relaxation programmes, or may be able to advise you on local community programmes.

Suggested websites

The following websites also have information on bowel cancer:

Macmillan Cancer Support (UK)

CancerHelp UK

Colorectal Surgical Society of Australia and New Zealand

Beating Bowel Cancer (UK)


This information was written in January 2018 by the Cancer Society. For cancer information and support phone 0800 CANCER (226 237)