Depending on their size and location in the colon, serrated polyps may become cancerous. Small, serrated polyps in the lower colon, also known as hyperplastic polyps, are rarely malignant. Larger serrated polyps, which are typically flat (sessile), difficult to detect and located in the upper colon, are precancerous.
They can occur anywhere in the large intestine or rectum, but are more commonly found in the left colon, sigmoid colon, or rectum.
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 sigmoid colon is the most common site for cancer of the colon. Rectal carcinoma is the most common cancer of the lower gastrointestinal tract.
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.
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.
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.
“Right-sided colon cancers tend to be asymptomatic or cause these symptoms only when they are at an advanced stage and fairly large. Right-sided cancers are more likely to be diagnosed at a later stage and this alone makes for a poorer prognosis,” Dr. Dakwar says.
Two thirds of patients (n = 36,066) had right-sided colon cancer, and one third (n = 17,735) had left-sided colon cancer.
The mean age for the onset of the disease is 16 years, but can occur early at 8 years of age. The number and size of polyps increase with time. Most of the CRC (about 70%) tend to occur in the left side, whereas, a small percentage (about 10%) occurs in the right side [38, 39].
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.
Most polyps grow slowly and take from between 10 and 15 years to become cancerous.
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.
The most common sites of polyps were sigmoid colon 28.6%, descending colon 23.2% and rectum 22.8%. Additionally, 86.5% of the patients had one polyp and 10.8% were presented with two polyps. 51.7% patients had sessile while 48.3% had pedunculate polyps.
Polyps are benign growths (noncancerous tumors or neoplasms) involving the lining of the bowel. They can occur in several locations in the gastrointestinal tract but are most common in the colon.
The three different polyps are villous, tubular and tubulovillous. Adenomatous polyps will gradually show dysplastic changes, which differentiates them from hyperplastic polyps. In general, colonic polyps are benign but those that develop high-grade dysplasia will become malignant with time.
Most colorectal cancers start as a growth on the inner lining of the colon or rectum. These growths are called polyps. Some types of polyps can change into cancer over time (usually many years), but not all polyps become cancer.
The 3 main symptoms of bowel cancer are blood in the stools (faeces), a change in bowel habit, such as more frequent, looser stools, and abdominal (tummy) pain.
On the other hand, right-sided colon lesions may produce vague abdominal aching, but are unlikely to present with obstruction or altered bowel habit. Other symptoms such as weakness, weight loss, or anemia resulting from chronic blood loss may accompany cancer of the right side of the colon.
Polyp Growth Rates
Cancerous polyps tend to grow slowly. It is estimated that the polyp dwell time, the time needed for a small adenoma to transform into a cancer, may be on average 10 years (17).
Signs and symptoms of colon cancer include: A persistent change in your bowel habits, including diarrhea or constipation or a change in the consistency of your stool. Rectal bleeding or blood in your stool. Persistent abdominal discomfort, such as cramps, gas or pain.
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.
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.
Colonoscopy at 3 years is recommended for patients with 3-4 polyps <1 cm in size or one polyp >1 cm. If there are 5 or more small or 3 or more larger polyps, then follow-up in one year is recommended.