Bowel / Colorectal cancer and polyps

What is bowel cancer?

Bowel cancer (also known as colorectal cancer) is a growth that can affect any part of the colon (large bowel) or rectum. You may also hear it referred to as colon cancer or rectal cancer, depending on where the cancer is located (with the rectum being about the last 15-20cm of your bowel).

1 in 13 Australians will develop bowel cancer in their life. This is one of the highest rates of bowel cancer in the world and within Australia, South Brisbane has the highest rate.

How does bowel cancer develop?

Almost all bowel cancers start as benign or harmless growths called polyps. Polyps are small bumps in the lining of the bowel. Some polyps (especially adenomas & sessile serrated polyps) have this potential to grow into a cancerous tumour. The vast majority of small polyps can be removed from the bowel at the time of a colonoscopy, removing the risk of that polyp developing into cancer.

bowel cancer

Image of a large “pedunculated” (stalked) colonic polyp at colonoscopy. This polyp may already have become cancerous.

What are the symptoms of bowel cancer?

Symptoms from bowel cancer can be quite variable. Any of the following symptoms can be indicative of bowel cancer and should be investigated:

  • Bleeding- ‘fresh’/ bright red or darker red/ maroon blood that is noticed in the stool, in the toilet bowl or on wiping.
  • Altered bowel habit- a change from your usual pattern (including loose motions/ diarrhoea, constipation, difficulty completely emptying, or a change in appearance with narrower shape of stool)
  • Pain- either abdominal or lower in the anus/ rectum
  • A noticeable lump or mass in your abdomen
  • Unexplained weight loss or anaemia (low blood count) causing tiredness

A colonoscopy is usually recommended to investigate these symptoms.

During the early stages of bowel cancer however, most people will have no symptoms at all. This is why screening is important.

You should never be told you are too young to have bowel cancer.

Don’t assume bleeding is always caused by haemorrhoids. All bleeding requires further investigation..

What is bowel cancer screening?

If you are aged 50 and over and don’t have a family or personal history of bowel cancer/ polyps, and have no symptoms (see those mentioned above) it is recommended that you participate in bowel cancer screening every 1-2 years. Screening involves a simple test that looks for tiny amounts of blood in your stool/poo (such a small amount that it is not visible when looking in the toilet bowl or on the toilet paper). The test involves placing small amounts of stool/ toilet water on a special card and sending it off to analyse for the presence of blood (faecal immunochemical test). These tests are available through your GP and some pharmacies.

In Australia, the government has implemented a National Bowel Cancer Screening Program (NBCSP). By 2020, everyone in the country aged 50-74 will receive a tax-payer funded screening test in the mail every 2 years. If blood is detected in the test, this does not definitely mean you have bowel cancer, but you will be notified of the result and will need further investigation with a colonoscopy within 30days.

What is bowel cancer surveillance?

Some people from families with bowel cancer/ polyps (including those with known inherited gene mutations), or those who have had polyps removed at colonoscopy in the past will require extra testing with a colonoscopy. This procedure will need to be repeated at regular intervals (anywhere from 1-5 years depending on the situation).

How is bowel cancer diagnosed?

If you have any concerning symptoms or a positive screening test (see above) a colonoscopy will be recommended to further assess. A bowel cancer can be diagnosed on inspection at the time of a colonoscopy, with small biopsies confirming the finding.

What is a colonoscopy?

A colonoscopy is a thorough and detailed examination of the entire lining of the large bowel (colon and rectum), and allows for procedures such as biopsies and removal of polyps.

This procedure involves a long, thin flexible tube with a ‘video camera’ at the tip – being passed through the rectum and large bowel.

A colonoscopy requires a certain amount of preparation (dietary modfications in the days prior and liquid medication to cause diarrhoea and clear the bowel) so an adequate view of the bowel lining is possible.

A light anaesthetic (sedative) is required. For safety, an anaesthetist will administer the sedation, monitor your vital signs during the procedure and make you as comfortable as possible. Very rarely, you may be slightly aware of what is going on in the room, but generally you won’t remember anything.

What are the risk factors for developing bowel cancer?

Most bowel cancers develop ‘spontaneously’ with no underlying predictable cause. Like most cancers, the risk of developing bowel cancer does increase with age with the majority of bowel cancers occurring in people over the age of 50yrs. Once again, this doesn’t mean that people under 50yrs should be complacent and ignore symptoms.

Similar to age, there are some other important risk factors that are unable to be changed (non-modifiable):

  • A personal history of developing polyps or bowel cancer and even other cases of cancer (eg. stomach and uterine). Some of these cancers may be caused by a similar cancer-causing gene abnormality.
  • Having a relative who had colorectal polyps or cancer. Sometimes people can be tested for inherited (familial) bowel cancer genes.
  • Having inflammatory bowel disease (ulcerative colitis or Crohn’s disease)

There are also other risk factors that can be changed (modifiable). There is convincing evidence that the risk of bowel cancer can be reduced through certain diet and lifestyle changes. These risk factors are:

  • Smoking
  • A diet high in red meats, processed meats, fried foods, alcohol
  • A diet low in fibre, vegetable, fruit and whole grain
  • Being overweight/ obese or physically inactive

How is bowel cancer treated?

Earlier diagnosis and better treatments have seen a significant improvement in survival rates from bowel cancer in Australia over the last 50yrs. If detected early (no spread of the cancer outside the bowel), the person can often be cured with high-quality surgery to remove a short length of bowel that contains the cancer. Depending on certain cancer factors (eg. size; location within the bowel) and patient factors (eg. previous abdominal surgery; other significant health issues) there are multiple surgical options available.

Cancers within the rectum (the last 15-20cm of the bowel) can be quite complex and very difficult to treat. You should definitely be seen by a colorectal surgeon regarding treatment of a rectal cancer. A colorectal surgeon has been extensively trained and is very experienced in treating rectal cancers; and studies have shown improved outcomes for patients treated by surgeons who have undergone specific training in rectal cancer treatment. Depending on the results of routine investigations/‘staging’, up to 50% of rectal cancers may require radiotherapy and even small amounts of chemotherapy prior to surgery. We routinely use a cancer multidisciplinary meeting to discuss any complex rectal cancer case where there are a number of treatment options. Different specialists attend including medical oncologists (chemotherapy specialists), radiation oncologists (radiotherapy specialists), radiologists and surgeons.

As experienced colorectal surgeons we offer multiple different surgical treatment options and will tailor the treatment for you individual situation:

  • Minimally invasive surgery- laparoscopic (‘keyhole’) and robotic surgery
  • Open surgery including extended resections (often utilising the assistance of other subspecialists) for large/ locally advanced cancers
  • Transanal full thickness excision of early rectal cancers, including TAMIS (transanal minimally invasive surgery)
  • Total mesorectal excision for rectal cancers, including transanal options (“taTME”)

Sometimes if the cancer is very close (within millimetres) of the anal canal, or involving the anal canal, patients require complete removal of the anus and rectum to achieve a good cancer result. This can result in having to have a permanent colostomy. We take time to explain this and encourage a second opinion to give reassurance that this is the best surgical strategy for these tumours. We also involve our stomal therapists at an early stage to allow patients to come to grips with what a colostomy is and how it may affect them.

When the cancer has spread outside the bowel (metastatic bowel cancer), surgery is usually combined with other treatment options to kill any remaining cancer cells, with chemotherapy being an important part of this treatment.

What sort of follow-up is required after treatment?

As our surgical techniques have evolved and improved, recurrence rates (the risk of your cancer coming back) have also decreased, however there is a chance that your cancer may return.

The risk of recurrence of bowel cancer is highest in the first 5 years after your surgery. As a result, we tend to follow-up very closely over this 5 year period. Follow-up involves a combination of:

  • Clinical review- assessment of symptoms and thorough examination, every 3-6 months over the first year and then often every 6-12 months ongoing for 5 years.
  • Colonoscopy- the first follow-up colonoscopy is usually performed 6-12 months after surgery, and then ongoing (anywhere from every 1-5 years depending on the findings/ number and type of polyps removed).
  • Investigations- a combination of imaging (eg. CT scans; PET scans) and tumour marking blood tests (eg. CEA= carcinoembryonic antigen) at defined intervals.

Please see the below links for further information: