Colorectal Cancer


Patient Information from CSSANZ Website


What is Bowel Cancer?


Bowel Cancer is an abnormal growth of cells lining the bowel forming a lump, called a malignant tumour. The cancer cells may spread outside the bowel from the primary cancer to lymph glands or other organs and these clusters of cells are called metastases or secondary cancer. The vast majority of bowel cancers involve the large bowel (colon and rectum); the small bowel is rarely affected.



How Common is Bowel Cancer?


In Australia and NZ bowel cancer is the most common internal cancer for both sexes combined. The disease is increasing as the average age of the population rises. More than 10,000 new cases are diagnosed in Australia and almost 3,000 in NZ each year. Australia and NZ are among the top 10 high risk countries in the world.



What is the Cause of Bowel Cancer?


The underlying cause of bowel cancer is not known. It is more common in developed countries and is thought to be due to the food we eat slowing the transit of stools through the bowel. This increases the exposure to the lining of the bowel by cancer-producing substances called carcinogens. Dietary factors therefore may be important as a causative factor. Genetic factors which you inherit from your parents are also important and research in genetics and molecular biology are increasing our knowledge of these inherited factors.



Is There Any Difference in Bowel Cancer in Men and Women?


Bowel Cancer is more common in men, and they are more likely to develop rectal cancer and have an overall slightly worse outcome. In women, cancer is more common in the colon than rectum.



What are my Risks of Developing Bowel Cancer?


Lifestyle issues may be important in reducing the risks. These include: regular exercise, maintaining ideal weight and eating a diet low in fat and high in fibre. Known factors that will increase your risk are:


  • A close relative with bowel cancer (parents, children or siblings)
  • Bowel polyps (abnormal growth of cells on the bowel wall that form a mushroom-like lump)
  • Inflammatory bowel diseases such as Ulcerative Colitis and Crohn’s Disease
  • Genetic conditions where there are multiple polyps (e.g. Familial Adenomatous Polyposis – FAP)



What are the Common Symptoms?


  • Change in bowel habit i.e. a recent onset of diarrhoea or constipation
  • Bleeding from the back passage or blood mixed in the stool
  • Abdominal pain that persists
  • A low blood count or anaemia

You should see your doctor if these symptoms persist and tests will be arranged.



What are the Tests?


If your doctor suspects you may have bowel cancer, internal examinations of the back passage and special tests will be organised. A referral to a Specialist Colorectal Surgeon may be arranged. Your doctor or specialist may perform:


  • A digital (finger) examination of the back passage
  • An endoscopic examination of the back passage, rectum and colon with either a rigid sigmoidoscopy (up to 20 cms), flexible sigmoidoscopy (up to 60 cms) or colonoscopy (all of the large bowel)
  • A sample of tissue may be sent for pathology during these internal examinations
  • An Xray that outlines the colon (CT colonography).
  • A scan of the abdomen i.e. CT scan
  • An internal ultrasound examination – Endorectal ultrasound
  • A scan of the pelvis and rectum i.e. an MRI scan.


After the results of these tests are available, your doctor or specialist would discuss a plan of management. It is best at this stage to be accompanied by a friend or relative to help you in understanding the explanation and treatment plan.



How is Bowel Cancer Treated?


The most effective treatment, with the aim of cure, is surgical excision of the involved bowel. This means removing 20 to 40 cms of the bowel, though longer lengths of the bowel may be removed. Chemotherapy and/or radiotherapy may be given either before or after surgery. The aims of this treatment are to reduce: the size of the cancer, the chance of spread and the chance of the cancer recurring. When used to prevent the spread of cancer, it is called adjuvant treatment. When cancer has already spread and cannot be completely removed, it is used to relieve symptoms and is called palliative treatment.



Will I Have a Permanent Bag (Colostomy) or Temporary Bag (Loop Ileostomy)?


If you have rectal cancer, you may require a permanent colostomy if the cancer is very close to the back passage. Developments in medical technology, especially surgical staplers and specialists training in colorectal surgery, have significantly reduced the need for a permanent colostomy. The vast majority of patients with bowel cancer will not need a colostomy. When modern techniques are used and the bowel is joined to the back passage, a temporary bag (loop ileostomy) may be necessary to reduce the complications of surgery. The temporary bag is usually closed at three to six months after surgery, depending on the need for adjuvant treatment.



What are the Prospects of Cure After Treatment?


The outcome (prognosis) will depend on several factors including:

  • The growth pattern of the primary bowel cancer
  • The depth the cancer has spread through the bowel wall
  • The presence of cancer cells in lymph glands and other organs
  • Your general health and well-being


Two thirds of people with bowel cancer can be cured if the diagnosis is made early and treatment performed promptly. If cure is not possible, recent advances in treatment can significantly reduce symptoms, especially pain.


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