If you have a history of adenomatous polyps (adenomas), you are at increased risk of developing colorectal cancer. This is especially true if the polyps are large, if there are many of them, or if any of them show dysplasia.
Anyone can develop colon polyps. You're at higher risk if you're 50 or older, are overweight or a smoker, or have a personal or family history of colon polyps or colon cancer.
Risk factors for metachronous high-risk colorectal neoplasms
Specifically, patients with 5 or more polyps at index colonoscopy had a significantly higher risk of metachronous HR-CRN (OR, 3.552; 95% CI, 1.522–8.290; p = 0.003).
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.
*For screening, people are considered to be at average risk if they do not have: A personal history of colorectal cancer or certain types of polyps. A family history of colorectal cancer.
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.
If you have one or two low-risk adenomas removed, you probably won't need another exam for five years. If you have more serious adenomas, you may need another exam sooner than five years. Very high-risk patients may need the test in just one to three years.
Small colon polyps are harmless. But over time, some do grow and become cancerous. There is no way to tell the difference between polyps that will turn into colon cancer and polyps that won't by simply looking at them. The polyps need to be removed and analyzed under a microscope in a laboratory.
If the polyps are larger (10 mm or larger), more numerous, or abnormal in appearance under a microscope, you may have to return in three years or sooner. If the exam finds no polyps, "your cancer risk is essentially the average for the population, and you can wait 10 years for the next screening," Dr. Saltzman says.
It takes approximately 10 years for a small polyp to develop into cancer. Family history and genetics — Polyps and colon cancer tend to run in families, suggesting that genetic factors are important in their development.
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.
People can have several polyps scattered in different parts of the colon. Some polyps can contain cancer, although the vast majority of polyps do not. Larger polyps are more likely to become cancerous than smaller ones.
Most polyps grow slowly and take from between 10 and 15 years to become cancerous.
Colon polyp development involves genetic and epigenetic changes and environmental effectors such as stress in this process can drive the normal colonic epithelial cells to hyperplastic and adenomas [25-27].
Bowel polyps are not usually cancerous, although if they're discovered they'll need to be removed, as some will eventually turn into cancer if left untreated. Some people just develop one polyp, while others may have a few.
The former has no potential to become cancerous, but adenomatous polyps can turn into cancer if not removed, and in adults, you have an increased chance of developing more polyps. Colorectal Surgical Associates will typically remove all polyps during a colonoscopy.
Polyps do not usually turn into cancer. But if some types of polyps (called adenomas) are not removed, there's a chance they may eventually become cancerous. Doctors believe that most bowel cancers develop from adenoma polyps. But very few polyps will turn into cancer, and it takes many years for this to happen.
Anywhere between 15 and 40 percent of adults may have colon polyps. Colon polyps are more common in men and older adults.
"Of all the polyps that we see, only a minority will turn into cancer," he says. "Sometimes they just go away on their own, but removing polyps is thought to be one of the mechanisms by which we can prevent the formation of cancer in the first place." That's why regular screening is so important.
Living with polyps
Treatment provides a good outlook. If you do not get your polyps removed, they can continue to grow. They may develop into cancer. If you've had polyps before, you are at greater risk of getting more.
There's no upper age limit for colon cancer screening. But most medical organizations in the United States agree that the benefits of screening decline after age 75 for most people and there's little evidence to support continuing screening after age 85. Discuss colon cancer screening with your health care provider.
The only way to be sure that a colon polyp has cancer is to remove the polyp and look at it under a microscope. But a colonoscopy may show some signs that there may be cancer.
Colonoscopy in very elderly patients carries a greater risk of complications and morbidity than in younger patients, and is associated with lower completion rates and higher likelihood of poor bowel preparation.
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.