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.
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.
There is no set size at which a polyp will become cancerous, nor any particular size that is always cancerous. Even among large polyps, the majority are not cancerous.
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.
Not all polyps will turn into cancer, and it may take many years for a polyp to become cancerous. Anyone can develop colon and rectal polyps, but people with the following risk factors are more likely to do so: Age 45 years and older. A family history of polyps or colon cancer.
If your doctor finds one or two polyps less than 0.4 inch (1 centimeter) in diameter, he or she may recommend a repeat colonoscopy in 7 to 10 years, depending on your other risk factors for colon cancer. Your doctor will recommend another colonoscopy sooner if you have: More than two polyps.
If the colonoscopy finds one or two small polyps (5 mm in diameter or smaller), you are considered at relatively low risk. Most people will not have to return for a follow-up colonoscopy for at least five years, and possibly longer.
The removed polyp tissue is checked for cancer by looking at it under a microscope. If cancer cells are found, surgery might be needed because the cancer may have spread beyond the polyp. But if your provider thinks the cancer is only in the polyp that was removed and hasn't spread, you may not need surgery.
Most colon polyps are harmless. But over time, some colon polyps can develop into colon cancer. Colon cancer can be fatal when found in its later stages. Anyone can develop colon polyps.
Colon cancers develop from precancerous polyps that grow larger and eventually transform into cancer. It is believed to take about 10 years for a small precancerous polyp to grow into cancer.
Research indicates that as many as 60 percent of polyps may grow back within three years. Also, about 30 percent of patients who've had polyps removed will develop new ones. This is why it is important to talk to the care team about follow-up screening within five years after the polyps are removed.
Cancerous polyps may cause no symptoms at all. But if you do have symptoms, they depend on where the polyp is located: Colorectal polyps may cause belly pain, constipation, diarrhea or blood in your poop. Stomach polyps may cause nausea, belly pain, vomiting and bleeding.
In most cases, no. Your doctor can't usually tell, simply by looking at a polyp during a colonoscopy, if it's cancerous. But if a polyp is found during your colonoscopy, your doctor will remove it and send it to a lab for a biopsy to check for cancerous or precancerous cells.
If the cancer is diagnosed at a localized stage, the survival rate is 90%. If the cancer has spread to surrounding tissues or organs and/or the regional lymph nodes, the 5-year relative survival rate is 74%. If the cancer has spread to distant parts of the body, the 5-year relative survival rate is 17%.
Usually, in the majority of cases, it takes around two to three weeks to recover from a colon polyp removal surgery completely.
People with very early colon cancer (stage 1) do not usually need chemotherapy. But this might change after surgery. After your operation, a specialist doctor (pathologist) looks closely at your cancer.
Right-sided polyps are more likely to develop into cancers — which often grow rapidly and have a higher risk for metastasis, spreading to distant body areas. Right-sided colon cancers also tend to develop from flat polyps rather than the usual mushroom-shaped ones, and are genetically atypical, too.
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.
Number and Size
Approximately 1% of polyps with a diameter less than 1 centimeter (cm) are cancerous. More than one polyp or a polyp that is 1 cm or bigger places you at higher risk for colon cancer. Up to 50% of polyps greater than 2 cm (about the diameter of a nickel) are cancerous.