The Stages of Bowel Cancer and Its Causes

We take a look at bowel cancer - what it is and what can cause it.

Bowel cancer is the second most common form of cancer affecting men and women in Australia. It’s estimated over 16,000 Australians were diagnosed with bowel cancer in 2014, about 13% of all cancers diagnosed that year. 

What is bowel cancer?

Bowel cancer is also known as colon cancer or colorectal cancer. It happens when cells grow abnormally and form lumps, often called polyps, in the colon or rectum (parts of the large intestine). 

These cancerous cells can then grow and spread through the bowel to other parts of the body (invasive cancer). This is why bowel cancer is commonly classified into 4 ‘stages’ based on how far the cancer has penetrated through the bowel wall. 

  • Stage I or A - The cancer is only on the surface of the bowel wall
  • Stage II or B - The cancer has spread to the outer surface of the bowel.
  • Stage III or C - The cancer has gone through the wall of the bowel into the tissues or lymph nodes beside the bowel.
  • Stage IIII or D (widespread) - The cancer has spread to other parts of the body, commonly the liver or the lungs. 

What can cause bowel cancer?

We don’t really know exactly what causes bowel cancer but it tends to be slightly more common in men, and mostly affects people over 50. 

Other causes of bowel cancer may include: 
  • Your genes. Two inherited conditions can increase your risk of developing cancer: familial adenomatous polyposis (FAP), where you develop a lot of non-cancerous lumps (polyps) in your colon; and Lynch syndrome, also known as hereditary non-polyposis colorectal cancer (HNPCC). People with a family history of bowel cancer are also more likely to get bowel cancer, although in 80% of bowel cancer cases there is no known hereditary genetic link.
  • Other long-term inflammatory bowel problems. Conditions such as Crohn’s disease and ulcerative colitis are linked with an increased risk of developing bowel cancer. 
  • Increased insulin levels. (eg Type 2 diabetes).
  • Poor lifestyle behaviours:
    • Eating lots of red and processed meat, while not eating a lot of fibre, fruit and vegetables.
    • Not being physically active.
    • Being overweight or obese.
    • Smoking.

Back to top