Nonneoplastic polyps include hyperplastic polyps, inflammatory polyps and hamartomatous polyps. Nonneoplastic polyps typically do not become cancerous. Neoplastic polyps include adenomas and serrated types. These polyps have the potential to become cancer if given enough time to grow.
Polyps are common in American adults, and while many colon polyps are harmless, over time, some polyps could develop into colon cancer. While the majority of colon cancers start as polyps, only 5-10% of all polyps will become cancerous. The size of a polyp typically does make a difference.
The large majority of polyps will not become cancers. Certain types of polyps are more likely to turn into cancer. Removal of polyps during a colonoscopy reduces the risk of developing colon cancer in the future.
Most polyps are benign (not cancerous). “However, many polyps are precancerous [adenomas], which, if they remain in place for over 5 to 7 years, may progress towards a cancer,” says Yale Medicine's Harry Aslanian, MD, a Yale Medicine gastroenterologist.
Polyps classified as adenomas are considered precancerous and should be removed. Larger polyps have a higher chance of becoming cancer than small polyps. Regular colon cancer screening gives you the best chance of catching adenomas before they become cancerous or catching colon cancer in the earliest stages.
How common are colon polyps? Colon polyps are common in American adults. Anywhere between 15 and 40 percent of adults may have colon polyps. Colon polyps are more common in men and older adults.
Adenomas: Many colon polyps are the precancerous type, called adenomas. It can take seven to 10 or more years for an adenoma to evolve into cancer—if it ever does. Overall, only 5% of adenomas progress to cancer, but your individual risk is hard to predict.
As a general rule, the larger the adenoma, the more likely it is to eventually become a cancer. As a result, large polyps (larger than 5 millimeters, approximately 3/8 inch) are usually removed completely to prevent cancer and for microscopic examination to guide follow-up testing.
These polyps have the potential to become cancer if given enough time to grow. Most of these colon polyps are called adenomas. Serrated polyps may also become cancerous, depending on their size and location in the colon. In general, the larger a polyp, the greater the risk of cancer, especially with neoplastic polyps.
How long does it take for a polyp to turn into cancer? The growth and mutation of colon polyps into cancer is a slow process, taking an estimated 10 years on average. So as long as patients are screened, it is unlikely they will develop cancerous polyps.
Most polyps are benign (not cancerous). Your doctor can tell if a colon polyp is cancerous during a colonoscopy by collecting tissue to biopsy. The results of the biopsy are typically sent to your doctor within a week. Only 5% to 10% of all polyps become cancerous.
Not all polyps are precancerous or cancerous. Sometimes the nature of a polyp can be distinguished based on how it looks during a colonoscopy. But only removal for examination under a microscope by a pathologist can accurately determine if a polyp is precancerous.
Polyps can range in size from the less-than-5-millimeter “diminutive” category to the over-30-millimeter “giants.”
The doctor will then send any removed polyps to a pathologist for a biopsy to see if cancer is present. If the biopsy reveals that cancer is present, then cancer specialists will outline a treatment plan for the person. Common treatments for colon cancer include surgery, chemotherapy, and radiotherapy.
Most polyps grow slowly and take from between 10 and 15 years to become cancerous. Due to this general time frame, most screenings are scheduled every 10 years which gives Colorectal Surgical Associates time to remove any polyps before they become cancerous.
Larger colon polyps are more difficult to remove, and require a specialist. If a routine colonoscopy screening reveals you have large colon polyps, your doctor may recommend that you have surgery. However, a less-invasive, endoscopic option exists for treating these growths in the colon.
Polyps that are too large or that can't be removed safely during screening are usually removed surgically, which is often performed by inserting an instrument called a laparoscope into the abdomen to remove the diseased portion of the bowel. Colon and rectum removal (total proctocolectomy).
They look like bumps growing from the inside lining of the bowel protruding out. They sometimes grow on a “stalk” and look like mushrooms. Some polyps can be flat. People can have several polyps scattered in different parts of the colon.
Giant lipomas (>4 cm) are the most common benign tumors in the colon that cause intussusception, although no specific incidence data have been documented. Even patients with large lipomas may have nonspecific or intermittent symptoms, which causes delay and difficulty in making the diagnosis.
In 1 to 7 years, depending on a variety of factors: The number, size and type of polyps removed; if you have a history of polyps in previous colonoscopy procedures; if you have certain genetic syndromes; or if you have a family history of colon cancer.
Polyps grow through rapidly dividing cells, which is similar to how cancer cells grow. This is why they can become cancerous, even though most polyps are benign.
Large polyps are 10 millimeters (mm) or larger in diameter (25 mm equals about 1 inch).
How long does it take a polyp to turn into a cancer? Generally, it's about a 10- to 15-year process, which explains why getting a colonoscopy screening once every 10 years is sufficient for most people. However, this chain of events may occur faster in people with hereditary colorectal cancer syndromes.
However, over time polyps can become large and malignant if they aren't treated. Many polyps are found to be pre-cancerous, which means they have the potential to turn cancerous if they aren't removed. With early detection through an endoscopic test, the risk can be eliminated by your gastroenterologist.