Bowel Cancer refers to cancer of the colon (large intestine) or rectum and will affect approximately 1 in 13 Australians over their lifetime. The majority of bowel cancers start from polyps, which are small growths on the inner lining of the bowel wall. Polyps are generally benign (non-cancerous), but certain types (adenomas) have the potential to transform into cancer. This process can take up to 10 years to occur and it should be remembered that only a small minority of polyps will eventually develop into cancer.
The risk of bowel cancer increases significantly after the age of 45, though can occur at a younger age. Only 1/3 of patients will have family history or hereditary predisposition to developing bowel cancer. Other factors that can contribute to an increased risk include smoking, being overweight, meat or processed meats, a history of diabetes and inflammatory bowel disease (ulcerative colitis and Crohn’s disease).
Bowel cancer may present with symptoms such as a change in bowel habit, abdominal pain, unintentional weight loss, rectal bleeding or a low blood count (anaemia) and low iron levels. However, a significant proportion of patients may not display any symptoms.
Bowel cancer screening is designed to identify polyps and cancer in healthy individuals over the age of 50. The main method of screening in Australia is through a test known as a faecal occult blood test, which detects the presence of blood in a stool sample. A positive result should prompt further investigation with a colonoscopy, as should the symptoms listed above. A colonoscopy can not only make or exclude a diagnosis of colon cancer but also identify and allow the removal of polyps. Individuals with a history of polyps or a family history of bowel cancer should consider colonoscopies every 5 years. Those with a first degree relative with a diagnosis of bowel cancer may require screening with colonoscopy rather than faecal occult blood testing.
The treatment of bowel cancer includes one or a combination of surgery, chemotherapy and radiotherapy depending on the size of the tumour and whether it has spread outside the bowel. Approximately 90% of cases can be treated successfully.