What is a colon polyp?
Colon polyps are growths that stick out from the lining of the lower intestine. People do not usually know the polyps are there unless they bleed or are found during an examination of the colon. Most polyps are small in size and usually do not cause any problems. They are benign and do not become cancerous. Larger benign polyps can interfere with health by making it more difficult to pass a bowel movement. Polyps may grow with or without a stalk; those without a stalk are more likely to be
cancerous than those with a stalk. Adenomatous polyps, which consist primarily of glandular cells that line the inside of the large intestine, are likely to become cancerous (that is, they are precancerous). Another type of colon polyp, called an adenoma, is potentially cancerous. Thirty percent of people over age 50 have at least one adenoma. Some adenomas stay harmless. However, others may turn into cancer. The larger the adenoma, the more likely that it will become cancerous. It takes about five years for a medium-size adenoma to develop and about ten years for a cancer to develop. This allows plenty of time to be tested.
Your digestive tract stretches from your mouth to your anus. As food travels along this 30-foot passageway, nutrients are broken down into a form that can be absorbed by your body and used to build cells and produce energy. The last part of your digestive tract is a long muscular tube called the large intestine. The upper 4 to 6 feet of the large intestine make up the colon, and the lower 8 to 10 inches make up the rectum. The colon's main function is to absorb water, salt and other minerals from digested food. Your rectum stores waste until it's eliminated from your body.
Polyps can develop anywhere in your large intestine. They can be large or small and may be flat (sessile) or mushroom shaped and attached to a stalk (pedunculated). In Greek, polyp means "many feet," a reference to mushroom-shaped polyps, which have been described as resembling toes. Small and mushroom-shaped polyps are much less likely to become malignant than are flat or large ones. In general, the larger a polyp, the greater the likelihood of cancer.
The three main types of colon polyps are:
Adenomatous polyps. Once these polyps grow beyond the size of a pencil eraser - about 5 millimeters (mm) or 1/4 inch - there's a small but increasing chance they'll become cancerous. This is especially true when their diameter exceeds 10 mm. For that reason doctors normally take a tissue sample (biopsy) from larger polyps during flexible sigmoidoscopy and either biopsy or remove most polyps during colonoscopy. Adenomas are divided into three sub-types - villous, tubular and tubulovillous. Villous adenomas tend to be larger than the other types and are the most likely to become malignant.
Hyperplastic polyps. These polyps occur most often in your left (descending) colon and rectum. Usually less than 5 mm in size, they're rarely malignant.
Inflammatory polyps. These polyps may follow a bout of ulcerative colitis. Although the polyps themselves are not a significant threat, having ulcerative colitis increases your overall risk of colon cancer.
Cancer affects your cells, the basic units of life. Healthy cells grow and divide in an orderly way to keep your body functioning normally. But sometimes this growth gets out of control — cells continue dividing even when new cells aren't needed. In the colon and rectum, this exaggerated growth may cause polyps to form in the lining of your intestine. Over a long period of time, some of these polyps may become malignant.
More information on colorectal cancer
What is colorectal cancer? - Colorectal cancer is cancer of the colon or rectum. Colorectal cancer includes cancerous growths in the colon, rectum, anus, and appendix.
What causes colorectal cancer? - Colorectal cancer is a disease resulting from mutations in epithelial cells lining the gastrointestinal tract.
What're the risk factors for colorectal cancer? - Risk factors for colorectal cancer include family history of colon cancer, age, smoking, diet, virus.
What're the symptoms of colorectal cancer? - Symptoms of colorectal cancer vary depending on the location of the cancer within the colon or rectum, though there may be no symptoms at all.
How is colorectal cancer screened and diagnosed? - Colorectal cancer usually is diagnosed by a sigmoidoscopy or colonoscopy. Screening for colorectal cancer is recommended in individuals who are at increased risk.
What's treatment for colorectal cancer? - Treatment for colorectal cancer depends mostly on the size, location and extent of the tumor. Surgery to remove the tumor is the most common treatment.
How to prevent the development of colorectal cancer? - Colorectal cancer can be associated with known risk factors. Many risk factors are modifiable though not all can be avoided.
What is a colon polyp? - Colon polyps are growths that stick out from the lining of the lower intestine. Polyps can develop anywhere in your large intestine.
What're the symptoms of colon polyps? - Smptoms of colon polyps include rectal bleeding, blood in stool, constipation or diarrhea, pain or obstruction.
What's the treatment for colon polyps? - For people with familial colon polyps, complete removal of the large intestine and rectum eliminates the risk of cancer.