Why do people develop bowel polyps and cancers?

Bowel cancer is one of the most common cancers in Australia.

Its presence is usually unexpected, and it often develops without any symptoms.

If you are aged 45 years or older, any bowel symptoms, a family history of bowel polyps or cancer, a diet that is high in meat, drinking alcohol, smoking and being overweight – all increase your risk of developing bowel polyps and cancer.

It is important to remember though, most people with bowel polyps and cancers have no family history, no symptoms and have a healthy lifestyle.

Bowel cancer is large bowel, or colorectal, cancer. Your entire large bowel from the end of your small intestine to the start of your anus, is lined by a single layer of cells, bowel-lining cells, or colonocytes.

Bowel cancer originates from these bowel-lining cells. This layer of cells is folded into little blind ended “wells”, what are strictly speaking called crypts.

Bowel lining cells are “born” from stem cells at the bottom of these crypts, grow on a conveyer belt to the top of the crypt, having done their job of absorption or secretion. These “old” cells then die and are shed into the bowel.

This conveyer-belt of life for bowel-lining cells, is fast and most of the cells are born, renewed and then die over the course of one week. Each time a new cell is formed, it is generated by one cell, becoming two.

The chances of a bowel polyp or cancer developing, therefore, is dependent on time (the opportunity for cell division and thus important DNA errors to occur) and exposure to a harmful environment that increases the risk of DNA damage and errors.

Got symptoms? Get tested. Fast access to testing supports early detection and that saves lives.

If you do experience symptoms, have questions or are feeling unsure about your health and your risks, talk to your GP.