precancerous polyps
Meaning of precancerous polyps: Growths on an internal lining that are not cancer, removed because a fraction of them would eventually have become cancer.
Definition of precancerous polyps
Precancerous polyps are lumps of tissue growing out from the lining of a hollow organ that carry a raised chance of turning into cancer over time. Most are found in the colon and rectum. They are not cancer when they are discovered, and taking them out prevents the cancer that a minority of them would otherwise have become.
Which polyps are precancerous and which are not?
| Type | Precancerous | Notes |
|---|---|---|
| Adenoma | Yes | The classic type; risk rises with size and with certain growth patterns |
| Sessile serrated lesion | Yes | Flat, pale and easily missed, with a different route to cancer |
| Hyperplastic polyp | Generally not | Common and small, particularly in the rectum |
| Inflammatory pseudopolyp | No | A tag of healing tissue left behind by inflammation |
How does a polyp become cancer?
Cells lining the bowel are replaced constantly. A gene fault in one of them lets its descendants multiply a little faster than they should, and the pile of extra tissue becomes a visible polyp. Further faults accumulate over years, the cells grow progressively more disordered, and eventually one group breaks through the thin layer beneath the lining. That crossing is what turns a precancerous growth into an invasive cancer with access to blood and lymphatic vessels. The whole sequence usually takes a decade or more, and that slowness is precisely what makes screening effective.
How are they found and removed?
Colonoscopy is the only test that both finds and removes them in one sitting, using a wire snare or fine forceps, painlessly since the lining carries no pain fibers. Everything removed is examined under a microscope, and the number, size and type found determine the interval before the next examination. Stool tests and computed tomography of the colon can detect polyps but cannot take them out.
Do they cause symptoms?
Almost never. A large one may bleed, visibly or in amounts detectable only by a stool test, and occasional large polyps produce mucus or a change in bowel habit. Because the great majority announce nothing at all, they are searched for rather than waited for, which is the reasoning behind colorectal cancer screening programs. Polyps also grow on other mucous membrane surfaces, such as the nose and the lining of the uterus, where the risks are different.
Also known as
Used in a sentence
Colonoscopy identified two precancerous polyps, both removed by snare and reported as tubular adenomas.
Good to know
Not every polyp is precancerous; small hyperplastic polyps carry little risk, while adenomas and sessile serrated lesions are the ones linked to colorectal cancer.
Word origin
Where “precancerous polyps” comes from
Polyp comes from the Greek polypous, meaning many-footed, a word first used for the octopus and later borrowed for growths that appear to cling by a stalk.