Although polyps can occur in linings of different regions of the body, including the female uterus, and the nasal cavity, today we will focus on those in the intestine, more specifically colon polyps.
A polyp is an outgrowth, or clump of cells that form on the lining of the colon. Although most polyps are benign (non- cancerous or harmless,) some have the potential to become malignant (or cancerous) over time.
Polyps are very common, occurring in anywhere between a third to one half of the adult population. Although they can develop in anyone, those who eat diets high in fat or low in fiber, have a family history of colon polyps or colon cancer, or are overweight or smokers, are more likely to develop colon polyps.
Colon Polyp Symptoms
Most polyps do not cause symptoms and are only found during routine screening tests for colon cancer. That being said, if they get large they will cause symptoms. Symptoms often include :
- Blood in your stool – blood can show up not only as red streaks or marks in the stool, it can also make bowel movements appear black (yes, black.) This is not always accurate though as some medications can make stools black, whereas beets and some other foods can make stool appear red.
- Rectal bleeding – contrary to blood found in the actual stool, blood can also be found on toiled paper after you’ve had a bowel movement. This can indicate not only colon polyps or colon cancer, but other conditions such as hemorrhoids or anal fissures.
- Changes in frequency or consistency – Changes in bowel habits that last longer than a week can indicate a presence of a large colon polyp which is obstructing the digestive tract and changing the appearance or timing of your bowel movements, this can also indicate a number of different conditions as well.
- Pain – In some cases a large colon polyp may partially obstruct your bowel, leading to cramps, abdominal pain, nausea, severe constipation, and vomiting.
Colon Polyp Diagnosis
Most polyps can easily be detected during a colon cancer screening examination such as a colonoscopy or sigmoidoscopy. These procedures are both very painless, and consist of examining the entire colon, (or only the end part called the sigmoid in the case of sigmoidoscopies,) with a very small camera attached to a very thin and flexible tube.
Another big sign of colon polyps is a positive fecal occult blood test (when a physician finds blood in your stool sample.) Other tests such as a stool DNA test (sDNA), and fecal immunochemical test (FIT) can be used to check stool samples for signs of colon cancer. X Rays can also be used in a computed tomographic colongraphy (CTC) to create a type of virtual colonoscopy where a physician can examine a detailed picture of the colon in a less invasive fashion to look for polyps.
Although many different options are available, doctors often recommend and prefer colonoscopies because it allows them to view the entire colon clearly, while removing any polyps at the same time. This can be helpful because they can also take samples and send them out for testing to determine the type of polyp it is. Even if doctors find polyps in another test, you will most probably then need a colonoscopy so the doctor can go and remove those polyps.
Causes and Risk Factors
Although most polyps are non cancerous, polyps are formed in a very similar fashion to cancer, through unregulated cell growth and division occuring in cells lining the colon. A mutation in any of the genes controlling cell replication can cause cells to continue dividing unnecessarily. Over extended periods of time, these polyps can possibly turn cancerous when left undiagnosed or untreated.
Polyps are very common in men and women of all races, especially those who live in industrialized countries, which suggests that dietary and environmental factors play a large role in their development.
The risk of polyps also greatly increases with age, with individuals over fifty with the highest likelihood to have colon polyps. It usually takes approximately 10 years for a small polyp to become cancerous, and therefore colon cancer screenings are recommended around the age of 45-50 for both sexes.
Polyps and colon cancer are both show are hereditary, which suggests that genetic factors are important in their development, and that any history of colon polyps or cancer in the family should be discussed with a healthcare provider. The importance of addressing this issue becomes even more urgent if cancer or polyps developed in those relatives at an earlier age. This is because there are genetic diseases that can make it much more likely that in individual develops colorectal cancer, or numerous polyps, relatively early in adult life.
FAP- Familial adenomatous polyposis is one such condition which leads to the early onset of thousands of adenomatous polyps throughout the colon. If left these polyps are left untreated, or even worse undiagnosed, they can lead to colon cancer in individuals as young as 35 years of age. FAP comes from an inherited mutation in a gene called APC ( adenomatous polyposis coli .) The diseases exhibits an autosomal dominant hereditary pattern, meaning that you only need one parent to carry the gene for it to be passed on to you.
HNPCC- Hereditary non polyposis colon cancer is another hereditary disease, which increases the risk of colon cancer, often beginning as early as 20 to 30 years of age. Although the risk of cancer increases tremendously, as opposed to FAP, it does not cause a large number of polyps. Testing for these genes is highly recommended for families with higher rates of colon cancer, but is unnecessary for others.
Types of Polyps
There are four main types of colon polyps, and although there are other types of polyps, they are far less common and will be discussed in a later article.
- Adenomatous- About two-thirds of all polyps fall in this category, and although only a small percentage of these become cancerous, nearly all malignant polyps are adenomatous. As a rule of thumb, it is said that the larger the adenoma, the more likely it is to become cancerous. Therefore larger polyps are usually taken for biopsy (a small tissue sample is taken for microscopic examination.)
- Hyperplastic- Hyperplastic polyps are usually small, and located towards the end portion of the colon. These cannot become malignant and are therefore not worrisome. The problem is that hyperplastic polyps cannot always be distinguished from adenomatous polyps through a colonoscopy, therefore hyperplastic polyps are also often biopsied and removed for further examination.
- Malignant- These are polyps that contain pre cancerous or cancerous cells, and are therefore the most worrisome. Treatment depends on the extent of the cancer as determined through microscopic examination, amongst other factors.
- Inflammatory- These polyps usually are found in individuals with ulcerative colitis or Crohn’s disease of the colon. Although the polyps themselves are non threatening, they indicate the presence of serious conditions which increase the risk of colon cancer.
Your risk of developing polyps and therefore colon cancer can be greatly reduced by having regular screening and making simple changes to your diet and lifestyle.
If polyps are detected, make sure to have regular follow up exams, as adenomatous polyps have a high risk of reappearing. There is a one in three possibility that adenomas will be present on a repeat colonoscopy done three years later, meaning that some of these were either to small to detect, or new polyps have developed. Therefore after polyps are removed, repeat colonoscopy is recommended every 3 to 5 years.
Colon Polyp Treatment
Since polyps must be examined by a pathologist to determine whether or not they are cancerous, your physician will most likely remove all polyps discovered during a bowel exam. Methods of removal include :
- Snare- Most polyps can be removed during the colonoscopy by snaring them with a wire loop that cauterizes it at the same time to prevent bleeding.
- Surgery- Larger polyps or those that cant be reached safely are surgically removed, using a laparoscopic techniques (which involves several small incisions in the abdominal wall, and instruments attached to cameras that display the colon on a monitor.)
- Colon and rectum removal- In cases of rare, inherited syndromes such as FAP, the surgeon may remove the entire colon and rectum while replacing it with a pouch which allows you to expel waste normally.
Justin Bokhoor – Medical Student
University of Miami Miller School of Medicine
© 2010 H.I.C. Digestive Health