Bowel Cancer

Patient Information

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.

Incidence

In Australia and New Zealand, bowel cancer is the very common. 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. It is more common in men and they are more likely to develop rectal cancer. In women, colon cancer is more common than rectal cancer.

Causes

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.

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 the risk include:

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)

Symptoms

Change in bowel habit

Bleeding from the anus/rectum 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.

Investigations

If your General Practitioner suspects you may have bowel cancer, internal examination of the back passage and special tests will be organised. A referral to a Specialist Colorectal Surgeon may be arranged. Your GP 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 20cms), flexible sigmoidoscopy (up to 60cms) or colonoscopy (all of the large bowel)
A sample of tissue (Biopsy) may be sent for pathology during these internal examinations
An X-ray 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 surgeon 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.

Treatment

The most effective treatment, with the aim of cure, is surgical excision or removal of the involved bowel. Chemotherapy and/or radiotherapy may be given either before or after surgery. The aims of these treatments 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.

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. Many 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.

Prognosis:

This depends on:

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.

Recovery and Follow- Up following treatment

Fatigue, abdominal discomfort and bowel irregularity are common symptoms whilst the body recovers and readjusts to the new arrangement of the bowel. These feelings may last for several months.

Your surgeon will arrange a schedule of follow-up that will extend for any years after treatment. At each follow-up appointment, internal examination of the bowel may be performed with some blood tests. Colonoscopy is usually performed initially at one to three years and then every three to five years after surgery. CT scans may also be required.

Can Screening Tests Detect Bowel Cancer?

A screening test is a test applied on the general population to detect the presence of cancer. Because bowel cancer starts on the lining of the bowel the abnormal growth can cause a small amount of invisible bleeding into the stool. A chemical test can detect that small amount of blood in the stool and this is called Faecal Occult Blood testing (FOB). This test is performed on samples of stool you collect yourself. Colonoscopy may also be used as a form of screening. Useful web sites for further information:

The Gut Foundation.

CSSANZ.