Testing for bowel cancer
There are a number of tests available, which are used to identify and diagnose bowel cancer. Your GP will determine the best method of testing for you based on any symptoms you may have and your family medical history, and make any necessary referrals to other medical specialists. These tests include:
- Rectal Examination
A simple test where the doctor inserts a gloved finger into the bottom (anus) to feel for anything unusual in the lower part of the bowel.
This test involves a rigid or flexible lighted telescope (sigmoidoscope) being inserted into the anus to examine the last few inches of the lining of the large bowel.
An examination using a flexible telescope passed into the bowel through the rectum, which enables the lining of the large bowel to be examined. Unlike x-rays, which take photographs, colonoscopy allows direct visual examination of the interior of the bowel and, in most instances, can provide substantially more detail and accuracy than an x-ray. Sometimes small samples (biopsies) are removed from the lining of the bowel so that they can be examined under a microscope to determine of there is any abnormality or pathology. In addition, if early growths called polyps are present in the bowel, they will usually be removed at the time of the colonoscopy.
- Faecal Occult Blood Test (FOBT)
Not a diagnostic test, but used to detect the presence of hidden blood in the faeces (bowel motion or stool), which may be an indication of a polyp or a cancer. Clinical trials have shown that population screening for bowel cancer using FOBT does reduce deaths from bowel cancer and these tests are considered the 'gold standard' for bowel cancer screening.
- Virtual Colonoscopy
A newer screening tool currently undergoing evaluation for accuracy and efficacy. The colon is inflated with air and a CT scanner image is taken. Virtual reality techniques construct a 3 dimensional image. If a polyp or growth is detected, a colonoscopy will be required to remove them.
- Barium Enema
A diagnostic test where small tube is inserted into the rectum and a liquid called barium is delivered. With air added, the barium is forced into the creases of the bowel wall and allows the bowel lining to be seen clearly when x-rays are taken. This method is less accurate than a colonoscopy.
Staging bowel cancer
Once a diagnosis with bowel cancer has been made, further tests such as MRI, CT and ERUS scans help to show if the cancer has spread to other parts of the body. This is called ‘staging’. Staging helps the specialists work out the best treatment options.
In Australia, the most commonly used bowel cancer staging system is the Australian Clinico-Pathological Staging (ACPS) system.
ACPS Staging System
Stage 1 - Cancer is found only in the bowel wall.
Stage 2 - Cancer has spread to the outer surface of the bowel wall.
Stage 3 - Cancer has spread to the lymph nodes near the bowel.
Stage 4 - Cancer has spread beyond the lymph nodes to other areas of the body, such as the liver or lungs.