Bowel | Chris O'Brien Lifehouse

(Colon, rectal and anal)

This information has been prepared to help you understand more about cancer of the large bowel. Cancers of the colon or rectum (colorectal cancers) are types of large bowel cancer.

Many people feel understandably shocked and upset when they are told they have bowel cancer. This information is intended to help you understand the diagnosis and treatment of bowel cancer.

We cannot advise you about the best treatment for you. You need to discuss this with your doctors. However, we hope this information will answer some of your questions and help you think about the questions you want to ask your doctors or other health carers.

The bowel

The bowel is part of the digestive system and is made up of two main components – the small bowel (small intestine) and the large bowel (large intestine). The large bowel has two major functions:

  • to finish digesting food by absorbing water and nutrients; and
  • to get rid of remaining wastes.

The large bowel has four main parts:

  • Caecum – A pouch at the beginning of the large bowel that receives waste from the small bowel.
  • Colon – The main working area of the large bowel, where water is removed. The colon is about 1.5 metres long and has four parts (the ascending colon, transverse colon, descending colon and sigmoid colon).
  • Rectum – The last 15 to 20 centimetres of the large bowel. The rectum stores waste (stools) until they are expelled during a bowel movement.
  • Anus – The opening at the end of the digestive tract.


What is bowel cancer?

Bowel cancer (also known as colorectal cancer) occurs when cells in the bowel become abnormal and grow uncontrollably. If left untreated, it can grow into the deeper layers of the bowel wall and can spread from there to the lymph nodes (glands).

Bowel cancer seems to start in one of two ways. It can grow from the inner bowel lining (mucosa), or it can develop from growths on the bowel wall called polyps. Not all polyps are malignant (cancerous); many are benign and harmless. However, polyps may grow and become cancerous over time.

How common is it?

If you would like to read any facts or statistics about bowel cancer, please refer to the Cancer Institute NSW website:

What is the cause?

  • Getting older – most people diagnosed with bowel cancer are over the age of 50.
  • Bowel diseases – having inflammatory bowel disease (such as Crohn’s disease or ulcerative colitis) significantly increase your risk, particularly if you have had the condition for more than 8-10 years.
  • Lifestyle factors – being overweight, having a diet high in fat or animal products, high alcohol consumption, smoking, and lack of physical activity.
  • Ashkenazi Jewish heritage – if you are from this background you have a higher risk.
  • Inherited genetic conditions – 5-6% of bowel cancers are caused by two conditions that run in some families, including (i) familial adenomatous polyposis (FAP), which is associated with the development of many polyps in the bowel; and (ii) Lynch syndrome, which was previously known as hereditary non-polyposis colorectal cancer.
  • Strong family history – if one or more of your family members (such as a parent, grandparent or sibling) have been diagnosed with bowel cancer, it may run in your family. This is also a possibility if two relatives on the same side of your family have had bowel cancer that was diagnosed before the age of 55.

What are the symptoms?

In its early stages, bowel cancer often has no symptoms. If you do experience symptoms, you may notice:

  • a change in your bowel habits, such as diarrhea, constipation, or smaller, more frequent bowel movements
  • a change in appearance of bowel movements (e.g. narrower stools or mucus in stools)
  • a feeling of fullness or bloating in the bowel or rectum
  • a feeling that the bowel hasn’t completely emptied
  • blood in the stools or on the toilet paper
  • unexplained weight loss
  • weakness or fatigue
  • rectal or anal pain
  • a lump in the rectum or anus
  • abdominal pain or swelling
  • a low red blood cell count (anaemia)

You may have nothing to worry about if you experience these symptoms, as they can all be caused by many other non-cancerous conditions. However, if you notice one or more of these symptoms you should bring it to the attention of your doctor for further investigation.


Cancer screening means looking for cancer in people who don’t have any symptoms. The bowel cancer screening test, known as the faecal occult blood test (FOBT), can find traces of blood in the faeces that are invisible to the naked eye but can be seen with a microscope. Because bowel cancer is one of the more common cancers, it is recommended that people aged 50 and older undertake a FOBT every two years. The Australian Government offers a free screening program (National Bowel Cancer Screening program) to people turning 50, 55, 60 or 65 years of age.

The FOBT can be done at home using a kit and then examined in the laboratory. FOBT cannot diagnose bowel cancer, but will give your doctor an idea of whether they should conduct further tests, such as a colonoscopy.


Your doctor will need to do a number of tests before they are able to diagnose bowel cancer. Initially you will undergo general tests to check your overall health and to look for any signs of cancer. If cancer is present, you will undergo further tests to see if the cancer has spread (metastasised).

Before some diagnostic tests, you will have to clean out your bowel. This is because stools impair the doctor’s ability to see inside your bowel. The cleaning process varies between hospitals but generally involves taking an oral laxative the day before the examination and having only clear fluids for 12-24 hours before the procedure.

If bowel preparation is required for your procedure you will be given instructions by your doctor.

General tests

Basic tests and procedures that can give an indication of whether or not cancer is present include:

Physical examination

Your doctor may feel your abdomen to check for swelling. The doctor will insert a gloved finger into your anus to feel for anything unusual in the anus and rectum. This is called a digital rectal examination (DRE). It may be a little uncomfortable, but it shouldn’t be painful.

Blood test

A blood test may be used to test your general health and measure your levels of carcinoembryonic antigen (CEA), which is produced by some cancer cells. CEA level is not always a reliable marker, so further tests may be done. Blood tests may also be used to measure chemicals in the liver and check your red blood cell count.

Flexible sigmoidoscopy

A sigmoidoscopy is a procedure that allows the doctor to see the rectum and the left side of the lower part of the colon. A flexible tube (sigmoidoscope) is put into the anus to and the bowel is inflated slightly. Any abnormalities can be seen with the camera and light at the end of the tube.

Your doctor may also use the sigmoidoscope to remove a piece of tissue (a biopsy) for examination. A sigmoidoscopy should take about 10-20 minutes. It may feel uncomfortable, but should not be painful.

Further tests

CT (computerised tomography) scan

Uses X-ray beams to take pictures of the inside of your body. You may be injected with a dye that makes your organs appear white on the scans. A CT scan is used to see if the cancer has spread. The scan itself takes 5-10 minutes and is painless.

MRI (magnetic resonance imaging) scan

Uses radio waves and a powerful magnet to create a cross-sectional image of the body. The image can show the difference between healthy and diseased tissue. MRI scans are painless, however some people find lying in the scanner noisy and claustrophobic.

PET (positron emission tomography) scan

Uses the emissions from a mild, radioactive glucose solution to create images that explain how certain organs or systems in the body are functioning. The solution circulates throughout the body and is taken up by actively dividing cells, such as cancer cells. It may take several hours to prepare for and have a PET scan.


Uses soundwaves to build up images of your body. A small device (called a transducer) is placed on or in your body. It sends out soundwaves that echo when they hit something dense, like an organ or tumour. There are two types of ultrasounds that you may have:

Abdominal ultrasound
This type of ultrasound is used to see whether bowel cancer has spread to the liver. The transducer is passed over your abdomen and an image is created on a screen.

Endorectal ultrasound (ERUS)
An ERUS is usually done if other tests have confirmed the presence of cancer in the rectum or anus. It helps to determine the size and spread of the cancer and may also help your doctor plan surgery. In an ERUS, a probe is inserted through the anus into your rectum. This can be uncomfortable, but only takes about 10 minutes.

Stages of bowel cancer

Working out how far the cancer has spread is called staging. Staging helps your doctor recommend the best treatment for you.

In Australia, the most common bowel cancer staging systems are the Australian Clinico-Pathological Staging (ACPS) and the TNM Classification of Malignant Tumours (TNM) systems:


Stage A: Cancer is found only in the bowel wall.

Stage B: Cancer has spread to the outer surface of the bowel wall.

Stage C: Cancer has spread to the lymph nodes near the bowel.

Stage D: Cancer has spread beyond the lymph nodes to other areas of the body, such as the liver or lungs.


T (Tumour) 1-4: indicates how far the tumour has grown into the bowel wall and nearby areas. T1 is a smaller tumour; T4 is a larger tumour.

N (Nodes) 0-2: shows whether the cancer has spread to the nearby lymph nodes. N0 means that the cancer has not spread to the lymph nodes; N1 means there is cancer in 1-3 lymph nodes; N2 means cancer is in four or more lymph nodes.

M (Metastasis) 0-1: shows if the cancer has spread (metastasised) to other, distant parts of the body. M0 means the cancer has not spread; M1 means the cancer has spread.


Prognosis means the expected outcome of a disease. Generally, the sooner cancer is diagnosed, the better the prognosis. Research has shown that 90% of bowel cancers are curable if found early.

You may want to discuss your prognosis with your doctor. It is important to understand that it is not possible for any doctor to predict the exact course of your disease. However, they will be able to consider your test results and other factors such as your age, fitness and medical history. These factors will help the doctor to decide, with you, on the best treatment options and let you know what to expect.

Which health professionals will I see?

You will be cared for by a range of health professionals who specialise in different aspects of your treatment. Health professionals who may care for you include:

  • General practitioner (GP) – arranges the first tests to investigate your symptoms or to follow up on an abnormal screening result.
  • Colorectal surgeon – diagnoses bowel cancer and operates on cancer in the large bowel and rectum.
  • Gastroenterologist – diagnoses bowel cancer and specialises in the digestive system and its disorders.
  • Medical oncologist – prescribes and coordinates chemotherapy.
  • Radiation oncologist – prescribes and coordinates radiotherapy.
  • Cancer care coordinator or clinical nurse consultant (CNC) – supports patients and families throughout treatment and liaises with other staff.
  • Nurses – care for you during and after surgery; help administer drugs; and provide information and support to you throughout all stages of your cancer treatment.
  • Stomal therapy nurse (STN) – provides information about surgery and adjusting to life with a temporary or permanent stoma.
  • Operating room staff (such as anaesthetists, technicians and nurses) – prepare you for surgery and care for you during the operation and recovery.
  • Dietician – recommends an eating plan to follow while you’re in treatment and recovery.
  • Social workers, counsellors, physiotherapists and occupational therapists – link you to support services and help with emotional, physical or practical issues.

For many people surgery is the main treatment for bowel cancer. However, you may also undergo chemotherapy, radiotherapy, or a combination of treatments.


The aim of surgery is to remove all the cancer and nearby lymph nodes. The type of surgery you have will depend on many factors, including your general health (i.e. whether you are fit enough to undergo major surgery), the stage of your cancer, the number of separate cancers within your large bowel, and the location of your tumour(s).

Local excision

People who have early stage tumour or who are not fit for major surgery may have a local excision. Unlike other surgical methods, this does not involve cutting into your abdomen. Instead, the cancer is removed by an instrument which is inserted into your rectum or colon.

There are several types of local excision – for example, transanal excision, transanal endoscopic microsurgery (TEMS) and, less commonly, a colonoscopic excision.

Surgery for cancer in the colon

The most common type of surgery is called a colectomy. You will be given a general anaesthetic and the surgeon will then make a cut in your abdomen to find the part of the colon containing the cancer. Some people have minimally invasive surgery – this is a term that describes surgical techniques using smaller cuts. This is sometimes called laparoscopic or keyhole surgery. Whether or not you can have minimally invasive surgery depends on the location of the cancer and its size.

The cancer, lymph nodes near the colon, and some normal bowel around the cancer will also be removed. The two ends of the bowel are then stitched or stapled back together. If the bowel can’t be joined together, one end will be brought through an opening in your abdomen. The opening (called a stoma) allows faecal waste to be removed from the body. This procedure is called a colostomy. In some cases, the surgeon may be able to rejoin your bowel at a later date. In other cases the stoma will be permanent.

Different types of colectomies may be carried out depending on where your cancer is located and how much of your bowel needs to be removed.

The six main types are:

  • Right hemicolectomy – the right side of the colon is removed
  • Left hemicolectomy – the left side of the colon is removed
  • Transverse colectomy – the middle part of the colon is removed
  • Sigmoid colectomy – the sigmoid colon is removed
  • Subtotal or total colectomy – most or all of the bowel is removed
  • Proctocolectomy – all of the colon and rectum are removed



Surgery for cancer in the rectum or anus

If you have rectal or anal cancer, your doctor may conduct an abdominoperineal resection/excision or anterior resection (high or ultra-low). Some people have minimally invasive surgery – this is a term that describes surgical techniques using smaller cuts. This is sometimes called laparoscopic or keyhole surgery. Whether or not you can have minimally invasive surgery depends on the location of the cancer and its size.

If you have rectal cancer, you may be given radiotherapy before surgery. Radiotherapy is generally given along with chemotherapy (known as chemo-irradiation). Having this treatment before surgery makes it easier to remove the cancer and lowers the risk that the cancer will recur.

The type of surgery you have will determine whether your bowel can be rejoined, and where in the rectum the join can be made. The main types of resections in the rectum or anus are:

CT (computerised tomography) scan

Your sigmoid colon and entire rectum and anus will be removed. Your surgeon will create a permanent stoma (colostomy), and waste will be removed through this opening. Afterwards, you will have two wounds: one on the abdomen and one where the anus was removed.

High anterior resection

The surgeon will remove the lower left part of your colon and the upper part of your rectum. Nearby lymph nodes and surrounding fatty tissue are also removed and the end of your bowel is rejoined to the top of the rectum.

Ultra-low anterior resection

The lower left part of your colon and your entire rectum will be removed. The surgeon will also remove nearby lymph nodes and some surrounding fatty tissue. The end of your bowel will be joined to the lowest part of your rectum. In some cases, the surgeon may create an internal pouch (colonic J-pouch) using the lining of the large bowel. The J-punch will be connected to the anus and work as a rectum.

If you have rectal cancer, you may be given radiotherapy before surgery. Radiotherapy is generally given along with chemotherapy (known as chemoirradiation).  Having this treatment before surgery makes it easier to remove the cancer and lowers the risk that the cancer will recur.

Side effects

You may experience a variety of side effects after surgery. Everyone who undergoes surgery will be left with a scar. Your scar(s) may be minimal if you have keyhole surgery, or more extensive (running from your navel to pubic area) if you have open surgery. Occasionally, surgery will cause nerve injury, which may lead to conditions such as erectile dysfunction.

Depending on how much of your bowel is removed, you may have to open your bowels more often or you may experience diarrhoea. You may need a temporary colostomy (stoma). If your surgeon can’t reconnect the healthy parts of your bowel, the large bowel will be connected to a permanent opening (stoma) on your body. For more information about coping with bowel changes, please refer to the Cancer Council NSW website:
‘Understanding bowel cancer after treatment’


Chemotherapy uses drugs to kill or slow the growth of cancer cells. These drugs are called cytotoxic. Chemotherapy kills rapidly dividing cells such as cancer cells. If your cancer is contained inside your bowel, surgery is usually the only treatment needed and chemotherapy is not used.

Chemotherapy may be given (either alone or alongside radiotherapy) before surgery to shrink the tumour and make it easier to remove. Alternatively, you may undergo chemotherapy after surgery if your cancer has not been completed removed or if it has spread to the lymph nodes.

Chemotherapy drugs are usually given by an injection into the vein (intravenously) or supplied in tablet form. You will probably have to visit the hospital or treatment centre daily (as an outpatient) to have your treatment. Your treatment will span a period of weeks or months, depending on the extent of your cancer and the purpose of chemotherapy.


Radiotherapy uses high-energy X-rays to kill cancer cells or injure them so they cannot multiply. It is used to prevent the cancer coming back or to destroy any cancer cells that may have spread to the lymph nodes.

Treatment is carefully planned to make sure all cancer cells are destroyed with as little harm as possible to your normal tissue. During radiotherapy, you will lie under a machine which shoots X-ray beams at the cancer. Each treatment only takes a few minutes once started but the whole process may take a few hours (including seeing your radiation oncologist, having blood tests and setting up the machine).

If radiotherapy is given along with chemotherapy for rectal cancer, you will probably have treatment from Monday to Friday for approximately 5-7 weeks. Usually you will be treated as an outpatient.


Palliative treatment helps improve quality of life by alleviating the symptoms of cancer without trying to cure the disease. Palliative treatment may include radiotherapy, chemotherapy and other medication and is particularly important for people with advanced cancer.

Sometimes treatment is concerned with pain relief and stopping the spread of cancer. In other cases, it manages emotional symptoms of cancer.

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