Colon polyps: causes, risks, treatment

Polyps in the intestine are not automatically dangerous. They can, however, because they can lead to colon cancer. Doctors therefore look specifically for polyps during a colonoscopy

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Colon polyps - briefly explained

  • Colon polyps are protrusions of the mucous membrane that occur mainly in the large intestine.
  • Most are harmless, but sometimes colon cancer can develop from them.
  • Polyps in the intestine rarely cause symptoms.
  • They can be identified and removed through a colonoscopy.
  • A healthy lifestyle prevents polyps.

What are intestinal polyps? Are they dangerous?

Many people have polyps in their intestines. The older you get, the more common they occur. Intestinal polyps are protrusions of the mucous membrane that protrude from the intestinal mucosa into the inside of the intestine - the intestinal lumen. They arise because more cells than normal grow in one or more places in the mucous membrane. The polyps are typically found in the large intestine, especially in the last section, the rectum.

Most colon polyps are benign, so colon cancer will not develop from them. However, some polyps can develop into colon cancer over the course of years. Initially, a tiny polyp forms - a polyp bud. This can increase over time. For various reasons, the polyp tissue can become malignant, usually over a period of many years. The cells in the tissue grow in an uncontrolled manner. This is known as colon cancer.

How cancer can develop from polyps:

© W & B / Jörg Neisel

Graphic: How does colon cancer develop from an intestinal polyp? An initially tiny increase in tissue - the polyp bud - increases in size over time. For various reasons, the polyp can become malignant. Then the tumor tissue grows uncontrollably and displaces healthy tissue. Colon cancer develops. This can spread into the underlying muscle layer, which is permeated by blood and lymph vessels.

Cancer cells can get to other parts of the body via the vessels and lead to daughter tumors (metastases). If the tumor is not discovered and continues to enlarge, it can completely fill the interior of the intestine and thus close it. If it grows outwards through the entire intestinal wall (break through), other organs can also be affected directly.

Classification of the types of intestinal polyps

There are different types of polyps. They differ in their shape and tissue structure (under the microscope):

  • Hyperplastic polyps: in the vast majority of cases, they are benign, sit directly on the mucous membrane and often look like a sawtooth.
  • Inflammatory polyps: do not degenerate and often occur in chronic inflammatory bowel diseases such as Crohn's disease and ulcerative colitis.
  • Harmful polyps: occur in people with hereditary syndromes and can develop in children.
  • Adenomas: are - besides the hyperplastic - the most common intestinal polyps and can be subdivided into further sub-forms. For example, they may look like a cauliflower and sit on a stem. But they can also lie flat on the mucous membrane or be a mixed form of both.

Once the polyps have been removed, the adenomas - also called adenomatous polyps - further differ in their appearance into tubular, villous, and tubulovillous adenomas. Furthermore, adenomas can look like a sawtooth (serrated adenoma). However, the doctor cannot reliably differentiate these polyp forms from one another during a colonoscopy, so the classification is always based on removal under the microscope. This also means that any polyps discovered must be removed.

Few adenomas develop into colon cancer. Nevertheless, they represent a preliminary stage of colon cancer, as doctors call the type of tumor. Because in over 90 percent of cases, colon cancer develops from adenomatous polyps. The more adenomas there are in the colon and the larger they are, the higher the risk of cancer.

In some people there is a large number of adenomas in the large intestine, which are hereditary. This clinical picture is called familial adenomatous polyposis (FAP). Without early cancer screening, almost 100 percent of these people develop colon cancer.

Colon Cancer Guide