Bowel cancer, or colorectal cancer, is the second most common cancer in both men and women. Bowel cancer is preceded by adenomas (polyps), which if undetected become invasive cancer.
Bowel cancer can start in the large bowel (which includes the colon and rectum) or the small bowel.
What Causes Bowel Cancer?
There are a couple of risk factors for developing bowel cancer.
- Diet: A high fat, high protein and low fruit and vegetable diet may increase the risk of developing bowel cancer.
- Genetics: Some genetic diseases put people at higher risk of developing bowel cancer. Go to our hereditary fact sheet for more information.
- Diseases: Diseases of the bowel lining, such as ulcerative colitis and Crohn’s diseases are a risk factor for bowel cancer.
What are the Symptoms?
- Blood in the stool (bowel motion)
- Diarrhoea or constipation with no obvious cause
- Unexplained weight loss
- Abdominal pain
TIP: If you have any of these symptoms you should have them checked by your doctor - but remember, they are common to many illnesses.
How is it Diagnosed?
Bowel cancer is generally diagnosed with a series of tests. These include:
- Colonoscopy: A procedure performed by a doctor whereby a tube with a camera is passed up the back passage. This allows the doctor to look for any abnormalities. A biopsy may be taken of tissues in the bowel.
- Physical examination: the doctor will feel the abdomen for any swelling. They will also insert a gloved finger into the rectum to feel for anything unusual.
- Blood test: a molecule called carcinoembryonic antigen (CEA) is produced by the bowel and some cancer cells. This can be a marker for cancer, but isn’t always.
- Faecal occult blood test: this measures traces of blood in the stool by microscope.
- CT Scan
- PET scan
Staging is when the extent of disease is determined. This helps the doctors plan treatment.
Cancer of the bowel is generally staged using the TNM system:
- T: Refers to tumour size
- N: If the cancer has spread to the lymph nodes
- M: If the cancer has metastasised (spread to another part of the body)
How is it Treated?
A team of doctors and other staff at the hospital will plan treatment. It will depend on the size of the tumour and where it is.
Treatment may be undertaken by an oncologist (a doctor who specialises in treating cancer with chemotherapy) a surgeon and a radiologist (a doctor who specialises in treating cancer with radiation).
Treatment may involve:
Surgery for bowel cancer
Surgery is the most common form of treatment for bowel cancer. The surgeon will cut out the tumour and then depending on the size and location, will try and repair the bowel as much as possible without having long term effects (such as a stoma).
Chemotherapy for bowel cancer
Chemotherapy is often given to treat bowel cancer after surgery. The aim is to destroy any left over cancer cells. This is known as adjuvant chemotherapy.
Chemotherapy may also be given before surgery to try and decrease the tumour size so it can be removed more easily during surgery. This is known as neo-adjuvant chemotherapy.
Radiotherapy for bowel cancer
Radiotherapy may be given before surgery to reduce the size of the tumour, or after surgery to destroy any remaining cancer cells.