Risk of cancer associated with a colon polyp less than 1cm is this 1%, 10% risk for a polyp between 1 and 2 cm and for polyps greater than 2 cm the risk is greater 25%-40%.
In general, the greater the villous component of the polyp, the greater the risk of malignant degeneration.
When pedunculated and the stalk greater than 2 cm. it is almost never malignant.
Flat polyps are more likely to occur on the right colon than the left.
Larger polyps than 10 mm in diameter if left intact progress to colorectal cancer at a rate of about 1% per year.
Greater than 1 cm present in 1-2% of screened population and smaller polyps may be present in 30% or more of such individuals.
Patients over the age of 50 approximately 40-50% have the development of a colon polyp.
There has been an increase in the prevalence of polyps 9 mm or larger in people younger than 50 years.
Only 8% of patients who undergo colectomy for a large, apparently benign polyp have cancer, meaning that 92% of patients have their colectomy removed for noncancerous reasons (Gorgun, E).
Male gender is significant risk factor for polyps.
Approximately half of patients with a polyp will recur with another polyp within 3 years, and approximately 10% will recur with an advanced polyp or multiple polyps.
Average annual rate of recurrence in patients who are over the age of 50 and who have no history of colon cancer is between 10-15% per year.
Patients who have a previous history of cancer have a higher risk of having recurrent polyps.
Patients with a family history of polyps and under the age of 50 years should consider diets with higher intake of vegetables, fruits and bran and increase exercise to decreased the risk of developing a colon polyp.
Dietary intervention is not effective inpatients in reducing risk for recurrent polyps.
Calcium intake is associated with reduced risk of recurrent polyps, but is also associated with an increased of prostate cancer in men.
Celecoxib causes a 28% reduction in mean number of polyps and a 30% reduction in the sum of polyp diameters.
NSAID’s decrease the risk for sporadic adenomas as well as cancer.
Sulindac decreases the number and size of adenomas following treatment with suldinac.
Hyperplastic polyps found in the left colon are not associated with polyps in the proximal colon.
Hyperplastic polyps are not adenomatous, and account for about half of all small rectosigmoid polyps.
Patients taking aspirin or NSAID’s on a regular basis have a roughly 50% less risk of development of colorectal polyps, colorectal cancer and a 50% reduction in cancer-associated mortality.
If a cancerous polyp has been completely resected at polypectomy, no additional surgery is necessary.
If deep invasion of cancer into the stalk has occurred or if adverse features such as grade 3 to 4 lesions, lymphatic invasion or positive margins are present, an en bloc colectomy is indicated.
Sessile serrated lesions and sessile serrated polyps are the precursors of 15 to 25% of colorectal cancers and are more difficult to detect endoscopically than conventional adenomas.
Serrated polyps represent a precursor lesion of colorectal cancer and contribute to approximately 1/3 of colorectal cancer cases through an alternative pathway.
The serrated pathway plays an important role in development of interval cancers, which occur despite appropriately timed endoscopic surveillance.
The serrated pathway is characterized by CpG island methylation phenotype, BRAF mutation, and often microsatellite instability.
Lifestyle factors such as smoking, and alcohol are associated with high risk of serrated polyps.
Higher vitamin D intake is associated with the lower risk of serrated polyps.