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 larger the polyp becomes, the bigger the risk of it developing into colon cancer.
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. Doctors remove all the adenomas they find.
If a doctor discovers polyps, they will often remove them via a colonoscopy or laparoscopy. 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.
Villous Adenoma (Tubulovillous Adenoma)
Approximately 15 percent of polyps detected in colon cancer screening are villous or tubulovillous adenomas. This type of polyp carries a high risk of turning cancerous.
Most polyps are benign, or noncancerous. However, since polyps are caused by abnormal cell growth, they can eventually become cancerous. Your doctor may want to perform a polyp biopsy to determine whether the growth is cancerous or benign.
A gastroenterologist, the specialist who usually performs a colonoscopy, can't tell for certain if a colon polyp is precancerous or cancerous until it's removed and examined under a microscope.
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.
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.
"Precancerous polyps are extremely common," he says. "We expect to find them in more than a quarter of the colonoscopies that we do at a minimum. So, you know, maybe a third or even a half of all patients getting [a] colonoscopy will have precancerous polyps."
If they found precancerous cells, there is no need for any additional treatment as long as they removed the entire polyp. Removing the tissue stops the development of cancer. Since you are still at an increased risk, we will likely recommend repeating the screening every three to five years in the future.
Colonoscopy is usually safe, but there is a risk of: Bleeding. If a polyp is removed or a biopsy is done during the colonoscopy, you might notice some blood in your stool for a day or two after the test. Serious bleeding is uncommon, but in rare cases, bleeding might need to be treated or can even be life-threatening.
Colon cancer, or cancer that begins in the lower part of the digestive tract, usually forms from a collection of benign (noncancerous) cells called an adenomatous polyp. Most of these polyps will not become malignant (cancerous), but some can slowly turn into cancer over the course of about 10-15 years.
These types of polyps are not cancer, but they are pre-cancerous (meaning that they can turn into cancers). Someone who has had one of these types of polyps has an increased risk of later developing cancer of the colon. Most patients with these polyps, however, never develop colon cancer.
Almost all precancerous polyps found during colonoscopy can be completely removed during the procedure. Various removal techniques are available; most involve removing them with a wire loop or biopsy forceps, sometimes using electric current. This is called polyp resection or polypectomy.
The size of a polyp typically does make a difference. The larger the polyp becomes, the bigger the risk of it developing into colon cancer. That risk increases significantly if the polyp is greater than 10 mm (1 cm); research has shown the larger a colon polyp becomes, the more rapidly it grows.
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.
Some types of polyps (called adenomas) have the potential to become cancerous, while others (hyperplastic or inflammatory polyps) have virtually no chance of becoming cancerous. The best course of action when a polyp is found depends upon the number, type, size, and location of the polyp.
A colonoscopy is the best way to diagnose and prevent bowel cancer. For most people it is a straightforward test. However, as with most medical tests, complications may occur. If you are at average or slightly above average risk of bowel cancer, screening every two years is recommended.
Results: Mean number of initial polyps were 2.2 and advanced polyps were observed in 40% of the patients. The cumulative recurrence rate of colon polyp was 13.8% within 1 year, and 60% within 3 years, while that of advanced polyps was 2.5% and 31% within 1 and 3 years, respectively.
Precancerous conditions of the colon or rectum are changes to cells that make them more likely to develop into cancer. These conditions are not yet cancer. But if they aren't treated, there is a chance that these abnormal changes may become colorectal cancer.
Can polyps come back? If a polyp is removed completely, it is unusual for it to return in the same place. The same factors that caused it to grow in the first place, however, could cause polyp growth at another location in the colon or rectum.
One factor is the location of the polyp. Detecting right-sided polyps can be more challenging due to the shape of colonic folds and need for complete colonoscopy. Right-sided lesions can be indicative of increased risk of recurrence of advanced adenomas.
Polyps are benign, meaning that they're not cancer and they won't spread, but over time certain types can develop into cancer. One of these types is called adenomatous polyps. These are known as pre-cancerous polyps. Polyps bigger than 1 centimeter have a greater cancer risk than polyps under 1 centimeter.