Colorectal polyps are growths in the colon and rectum, which can be seen in up to 20% of adults. While the vast majority of polyps are benign, if they are left untreated, some polyps can develop into colon or rectal cancer. It is important to note, however, that not all cancers start out as polyps.
What Causes Polyps?
Most polyps begin as abnormal clusters of cells that grow slowly over a number of years. It is unclear what the exact cause is, but most researchers agree that polyps develop from a combination of environmental as well as genetic factors. Over time, these clusters continue to grow and some may degenerate first into dysplasia (which is a precursor to cancer) and then into cancer. The vast majority of polyps are smaller than 2 cm in size when they are found, which typically happens during a colonoscopy.
Are Polyps Dangerous?
Most colorectal polyps are benign, although certain types have a higher risk of turning into cancer if they are not removed. Polyps are usually asymptomatic (not causing signs or symptoms), meaning that without colonoscopy or other screening tests, people don’t know they have them. Rarely, large polyps may bleed or cause a positive guaiac stool test. This is also known as the Fecal Occult Blood Test, which is a non-invasive, stool smear test designed to identify traces of blood in the stool. When polyps are found during a colonoscopy, they are removed to prevent them from potentially turning into cancer. The process is called a polypectomy. Occasionally, large polyps are difficult to remove during a colonoscopy, and may require surgery with removal of part of the bowel. After a polyp is removed, a follow-up colonoscopy is recommended. The time period between removal and follow-up depends on the type and size of polyp, as well as other variables.
Types of Colorectal Polyps
There are different types of colorectal polyps, and some pose a greater risk for developing colorectal cancer than others. Some polyps grow flat in the colon or rectum, and these are called flat or sessile polyps. Other polyps develop a stalk that causes them to protrude into the intestinal canal. Polyps are further characterized by the types of cellular growth patterns of seen under the microscope.
The more common types of polyps that develop on the lining of the intestine are:
- Adenomatous polyps: Also called adenomas, adenomatous polyps are precancerous growths. They may have villous, tubular or tubulovillous features under the microscope, which describes the pattern of abnormal growth. Generally, polyps with villous features are more worrisome. Two-thirds of colorectal polyps are adenomatous. Adenomatous polyps require ongoing colonoscopies (surveillance) when found and treated.
- Hyperplastic polyps: Small serrated polyps in the lower portion of the colon are called hyperplastic polyps, and these growths are quite common and rarely cause cancer. Depending on the circumstance, often they don’t require close surveillance.
- Serrated polyps: These are a “cousin” of hyperplastic polyps, which are often flat and are precancerous in nature. Large serrated polyps are usually located in the upper colon and are directly attached to the intestinal lining. Serrated polyps require ongoing colonoscopies (surveillance) when found and treated.
- Inflammatory polyps: Some polyps form as a consequence of colorectal disorders like ulcerative colitis or Crohn’s disease. Although not in and of themselves considered precancerous, the diseases that cause inflammatory polyps may increase the risk of colon cancer.
Signs and Symptoms of Polyps
Polyps in the colon or rectum are often asymptomatic, and are most often discovered incidentally during routine medical screening. However, colorectal polyps sometimes cause one or more symptoms. Polyps in the colon or rectum can cause bleeding. Blood in the stool and rectal bleeding are both symptoms associated with colorectal polyps. Another possible effect of colorectal bleeding caused by polyps is iron deficiency anemia, a disorder that can cause fatigue. Rarely, a change in bowel movements can be a sign of colorectal polyps, and patients may experience bouts of diarrhea or constipation. In addition, large polyps can cause nausea, vomiting, and/or abdominal cramps or mechanical obstruction of the bowel.
Evaluation and diagnosis of colorectal polyps requires endoscopic evaluation most often with colonoscopy. Flexible sigmoidoscopy (shorter scope passed only up to the lower third of the colon) maybe used as well, but this procedure is generally replaced by full colonoscopy. Occasionally, radiology tests such as barium enemas or CT scans may reveal abnormalities suspicious in appearance for polyps. When this happens, a full colonoscopy is warranted. Patients tested with stool samples that reveal the presence of blood (a possible sign of polyps or cancer) often then undergo colonoscopy.
The most common scenario for endoscopic diagnosis of colon polyps is the asymptomatic patient. However, other common situations can arise that prompt colonoscopy and detection:
- Presence of symptoms: If you have bowel changes that last longer than a week, abdominal pain or cramping, or there is blood in your stool, you should be tested for polyps.
- Age 50 or older: Experts recommend regular polyp screening starting at age 50, because colorectal polyps are more likely to develop with age. Precancerous colorectal polyps affect up to 40% of the population over the age of 60. African Americans are urged to begin screening at age 45.
- Family history of colon cancer or polyps: Polyps of the colon and rectum are more common in people with family members who have polyps and related diseases. In addition to a family history of colorectal cancer, several other hereditary disorders can increase the risk for developing polyps of the colon or rectum.
There are numerous behavioral and genetic risk factors that increase the odds that a person will develop polyps in the colon or rectum. The following are all issues that may contribute to a person’s risk for developing polyps:
- Obesity: Being obese doubles a person’s risk for developing colorectal polyps.
- Age: The older a person is, the more likely it is that he or she will develop polyps.
- Smoking: Individuals who smoke experience polyps of the colon or rectum at a rate twice to three times higher than that of nonsmokers.
- Alcohol use: People who consume alcohol are also at an increased risk for developing colorectal polyps.
- Inactivity: People who do not exercise have a higher risk of developing polyps.
- Race: African-Americans suffer from colorectal polyps at a higher rate than other racial groups.
- Genetic disorders: Some hereditary diagnoses cause polyps. For example, Lynch Syndrome and serrated polyposis syndrome are genetic disorders that cause colorectal polyps.
- Uncontrolled Type 2 Diabetes: People with untreated Type 2 Diabetes are at an increased risk for colorectal polyps.
Colon Cancer and Polyp Screening Recommendations
For average risk patients (those without a family history or personal of colon or rectal polyps (adenomatous), cancer or inflammatory bowel disease) the most common approach is colonoscopy every 10 years starting at age 50. Screening colonoscopies starting at age 45 in the African-American population are generally advised, due to this demographic’s increased risk for more aggressive colorectal cancers. Alternatives to colonoscopy every 10 years may include:
- Fecal occult blood testing yearly, with flexible sigmoidoscopy every 5 years
- Flexible sigmoidoscopywith dual air and contrast barium enema every 5 years
For patients at increased risk for developing polyps or cancer (family history or colorectal cancer or polyps (adenomatous)) more frequent and earlier studies are required. Several scenarios may commonly arise when discussing a patient’s family history including:
- patient with 1 first degree relative (parent, sibling, child) with cancer/polyp diagnosed prior to age 60
- patient with 2 first degree relatives at any age with cancer/polyp
Start with colonoscopy at age 40, or 10 years younger than the youngest family member (whichever is earlier), and follow up with colonoscopies every 5 years
- patient with 1 first degree relative with cancer/polyp diagnosed at 60 or over
- patient with 2 second degree relatives (grandparent, aunt, uncle) with cancer/polyp diagnosed at any age
Start with colonoscopy at age 40 and follow up every 10 years.
- patient with 1 second degree relative or third degree relative (great grandparent, cousin) with cancer at any age
Start colonoscopy at age 50 and follow up every 10 years
Certain colorectal cancers may arise with known genetic abnormalities such as in the case of Familial Adenomatous Polyposis syndrome (FAP) and Hereditary Nonpolyposis Colorectal Cancer syndrome (HNPCC). These represent unique clinical and genetic conditions requiring more extensive cancer screening and management. They are most commonly suspected and diagnosed when patients have multiple first and second degree relatives diagnosed at early ages with large numbers of polyps, colon cancers or other tumors. Management often involves colonoscopies beginning in the teens or early twenties and most commonly requires surgery. Genetic testing is often indicated.
Colon Cancer and Polyp Surveillance Recommendations
Patients with known prior adenomatous polyps generally require colonoscopies more frequently than every 10 years, due to the increased likelihood of developing more polyps. Subsequent colonoscopies are referred to as surveillance colonoscopies, due to this prior personal history. Factors that influence the timing interval for the follow up colonoscopy include the size, number, shape, microscopic appearance (ex. villous features) and the ease of removal of the polyp(s). Most intervals are of the 5, 3 or 1-year variety.
Patients with prior colorectal cancer typically require more frequent surveillance colonoscopy routines.
Patient First Approach
The medical experts at Saleeby and Wessels Proctology provide a wide array of colorectal services to Triangle-area residents. Using a Patient-First approach, the doctors at Saleeby and Wessels give patients thorough diagnostic and treatment information using minimally invasive techniques geared towards your personal comfort and understanding of colorectal health.
If you are in need of colorectal services such as flexible sigmoidoscopy or colonoscopy, contact Saleeby and Wessels today to learn how our seasoned and compassionate staff can serve you!