Colon cancer usually starts in an area of excess tissue growth in the inner lining of the colon or rectum called a polyp. Colon polyps occur in about 25% of the population over the age of 50. A small percentage of polyps may eventually progress to cancer and this usually takes several years.
How Polyps Become Cancer
Polyps in the colon arise from uncontrolled multiplication of cells leading to growth of tissue. This can occur due to mutation in the genes of the cells. If a polyp continues growing and invading the surrounding tissues it is considered cancerous. Larger polyps are more likely to become cancer.
Types of Polyps
There are different types of colon polyps:
- Hyperplastic: These are small tissue growths that have a low risk of becoming cancer.
- Inflammatory: This type of polyp develops as a reaction to inflammation from certain conditions such as Crohn’s disease or ulcerative colitis. It does not usually turn cancerous.
- Adenomatous: This accounts for 70% of all colon polyps and cancers usually develop in this type of polyp though only a small percentage of them (5%) actually become cancerous.
- Serrated: This type of polyp can become cancerous depending on its location and size.
Polyps may be pedunculated (growing on a stalk) or sessile (flat growths that can be difficult to detect and remove)
Colon cancer screening is recommended to help identify polyps and cancerous changes so that early treatment may be instituted. Colon cancer detected in the late stages is difficult to treat and can be fatal. Regular screening is recommended over the age of 50 but how often depends on your individual risk.
What Increases Your Risk of Developing Colon Polyps and Cancer?
Colon polyps and cancer are more likely in those with:
- A positive family history
- Inflammatory Bowel Disease
- Smoking or Alcohol use
- A sedentary lifestyle or lack of exercise
Removal of polyps helps reduce the risk of colon cancer. Polyps may be removed during a minimally invasive procedure called a colonoscopy. Large polyps may require surgery.