Johns Hopkins Health Alert
Do Colon Polyps Always Lead to Colon Cancer?
A reader of our Colon Cancer Special Report asks: If a person has polyps, what are the chances that cancer will develop? Because this question is important to all of us, we want to share the information in this Health Alert.
Some people are more prone than others to develop polyps, especially those with a personal or family history of colorectal cancer, those who carry specific genes for colorectal cancer and those with type 2 diabetes. Most of these polyps remain benign. But some, known as adenomatous polyps (or adenomas), have a high potential for developing abnormal cells, becoming precancerous and, eventually, evolving into cancer.
Adenomas usually grow on a stalk, resembling small mushrooms. However, they can also be flat or even slightly depressed nonpolypoid adenomas. They tend to grow very slowly over a decade or more. The risk of developing cancer increases with their increasing size and with the amount of time they have been growing in the colon.
- Fewer than 10 percent of all adenomas become cancerous. But more than 95 percent of colorectal cancers develop from adenomas, and doctors now think some other types of benign polyps also may become cancerous. For this reason, doctors usually recommend removing all polyps.
Small polyps can be removed painlessly during a colonoscopy or sigmoidoscopy. They are snared and severed with a retractable wire loop that is passed through the scoping instrument. Very small polyps may be destroyed with a small burst of electrical current.
Another precancerous condition seen in the colon is an abnormal cell growth or inflammation called dysplasia. The polyps and areas that look abnormal are biopsied and sent to be tested for malignant cells. If they are benign -- as many are -- no further treatment is needed, but you may be asked to have scoping exams within a few years to follow up.
If polyps or lesions are not benign but show signs of abnormal cells or cancer, your doctor will follow up with diagnostic tests and treatments. Very large polyps also may require surgery, whether they are benign or cancerous. Other types of cancers occur in the colon, but these are much less common. These include lymphomas, which are cancers of immune system cells, and carcinoid tumors and gastrointestinal stromal tumors, which develop from specialized cells in the intestine.
Posted in Colon Cancer on December 7, 2011
Medical Disclaimer: This information is not intended to substitute for the advice of a physician. Click here for additional information: Johns Hopkins Health Alerts Disclaimer
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