A: Colonic polyps are collections of cells arising and protruding from the inside lining of the colon. About two-thirds of colonic polyps are benign tumors (non-cancerous adenomas), most others being hyperplastic tissue (abnormal proliferation of cells) or other benign growths.
Q: I had a screening colonoscopy and they found two tubular adenoma polyps. Does this mean I will get colon cancer?
A: Colonic polyps are collections of cells arising and protruding from the inside lining of the colon. About two-thirds of colonic polyps are benign tumors (non-cancerous adenomas), most others being hyperplastic tissue (abnormal proliferation of cells) or other benign growths; a small percentage of polyps, more commonly large ones, have cancer cells in them.
Polyps usually do not cause any symptoms. Typically, they are found incidentally on a screening test; uncommonly, they cause bleeding (usually microscopic amounts of blood in the stool, but on rare occasions, visible rectal bleeding) or even obstruction of the colon.
Prior to age 40, colon polyps are uncommon, occurring in only a small percentage of the general population; however, in certain conditions –– such as familial adenomatous, familial juvenile or hyperplastic polyposis, Lynch, Gardner, Turcot or Peutz-Jeghers syndromes, hereditary non-polyposis, Cowden disease or other rare syndromes –– polyps do occur at young ages.
As people age, colonic polyps become much more common. They are found in over 25 percent of people over age 50 and about half of people over age 70. They are more common in men than women, and they are more common in people with a family history of polyps.
Over the course of five to 10 years, about 1 percent of polyps transform into colon cancer. All colon cancers begin as polyps; this is why polyps are concerning. The specific risk for an individual patient depends on the number, size and type of polyps –– larger numbers, larger size and more advanced types of polyps increase risk –– as well as other risk factors like a family history of colon cancer.
Since colon cancer is the third most common cancer, with well over 100,000 people diagnosed in the U.S. every year, screening for this disease is a good idea. The Centers for Disease Control recommend routine screening beginning at age 50 with either high-sensitivity fecal occult blood testing –– an annual testing of stool samples for microscopic blood ––sigmoidoscopy or colonoscopy –– including virtual colonoscopy, like President Barack Obama had, where the colon is visualized using a specialized CT rather than a colonoscope, which is a long, thin, flexible device with a camera on the end inserted into the anus to allow direct visualization of the colon.
For those at higher risk, such as those with a family history of early colon cancer or with one of the polyposis syndromes, screening beginning at a younger age may be indicated.
When polyps are identified on screening, they are typically removed. This can be done during the colonoscopy, hence the reason it is recommended as the preferred screening method by many experts. Removal may be done using a snare to “lasso” the polyp while sending energy through the snare’s metal loop to cut through the polyp and cauterize its base. Other methods to remove polyps include using other snares or certain types of forceps through a colonoscope as well as surgery.
Complications from colonoscopy and polyp removal can occur, including perforation (estimated to occur in 1 of every 300 to 800 colonoscopies with polyp removal) and bleeding. In addition, colonoscopy is estimated to miss about a quarter of polyps less than 5 millimeters and 1 in 20 as large as 10 millimeters, and there is a theoretical concern that the base of a removed polyp may subsequently recur.
Jeff Hersh, Ph.D., M.D., can be reached at DrHersh@juno.com.