Polyps are abnormal growths rising from the lining of the large intestine (colon or rectum). The rectum is the last 12 inches of the large intestine. Polyps may be flat (sessile) or develop on a stalk like broccoli. This is called a pedunculated polyp. Polyps are one of the most common conditions affecting the large intestine, occurring in 15-20 percent of the adult population. Most polyps are asymptomatic and never turn into cancer. However, a small percentage of polyps can slowly grow and develop over 8 to 10 years into rectal cancer. Almost all rectal cancers develop from polyps.
Malignant potential of polyps is associated with the presence of dysplasia or pre-cancerous changes, the type of polyp, and the size of the polyp.
Types of polyps
Tubular adenoma – 5% risk of cancer
Tubulo-villous adenoma – 20% risk of cancer
Villous adenoma – 40% risk of cancer
Size of polyp
<1cm – <1% risk of cancer
1-2cm – 10% risk of cancer
>2cm – 15% risk of cancer
What are the symptoms of rectal polyps?
Rectal polyps are usually not associated with symptoms. When they occur, symptoms include rectal bleeding, bloody stools, mucous discharge, mass, protrusion from the anus, and abdominal pain. A change in bowel habits may occur including constipation and diarrhea.
How are rectal polyps diagnosed?
Many rectal polyps can also been diagnosed in the office on digital rectal exam or flexible sigmoidoscopy. Rectal polyps are also diagnosed either by looking at the colonic lining directly with a colonoscopy or by X-ray with a virtual colonoscopy or barium enema. During a colonoscopy, your doctor spends the majority of the examination looking for changes to the normal landscape of the colon lining and removing anything that looks suspicious for a polyp. Since there is no fool-proof way of predicting whether or not a polyp is or will become cancer, all polyps should be removed.
How are rectal polyps treated?
Most polyps can be removed simply and safely at the time of your colonoscopy. Colonoscopies can actually prevent cancer from developing by removing the polyps before they become cancerous.
If a rectal polyp is too large it may require surgical intervention. If the polyp is low in the rectum, it can be removed by transanal excision. Under general anesthesia, the polyp is removed through the rectum with minimal discomfort and a quick recovery. Many times this can be done as an outpatient or overnight stay. If the polyp is higher in the rectum, it can be removed with a new technique, TAMIS, which stands for TranAnal Minimally Invasive Surgery.
What is the prognosis of rectal polyps?
People with a history of polyps have an increased risk of developing polyps again in their lifetime and should have regular exams by a physician specially trained to treat diseases of the colon and rectum.