Colon Polyps May Develop Without Causing Symptoms

Colon polyps are relatively common, particularly as people grow older. Most people with colon polyps do not experience symptoms and can continue their daily activities as usual. As a result, many people are unaware that they have polyps until they undergo colorectal cancer screening or a colonoscopy.

Most colon polyps are not cancerous. However, certain types can gradually change and develop into colorectal cancer over time. Detecting and removing polyps before they become cancerous is therefore an important part of colorectal cancer prevention.

1. What Are Colon Polyps?

A colon polyp is a growth that develops from the inner lining of the colon or rectum. Polyps may appear as raised growths, have stalks resembling mushrooms, or lie flat against the intestinal lining.

A person may have a single polyp or multiple polyps. Their size may range from only a few millimeters to several centimeters. The shape and size observed during a colonoscopy may not be sufficient to determine the exact type of polyp or how likely it is to become cancerous.

After a polyp is removed, it is sent to a pathologist for examination under a microscope. This examination helps determine the type of cells, the degree of abnormality, and whether cancer cells are present. The results allow the doctor to develop an appropriate follow-up plan and determine when the next examination should take place.

2. Types of Colon Polyps

Colon polyps can be classified into several types according to their cellular characteristics. Important types include adenomatous polyps, serrated polyps, inflammatory polyps, and hamartomatous polyps.

2.1 Adenomatous Polyps

An adenomatous polyp, or adenoma, develops from glandular cells in the intestinal lining and is considered a type of precancerous lesion. Finding an adenomatous polyp does not mean that a person has cancer, as most adenomas do not develop into cancer. However, the risk may increase when a polyp is large, when multiple polyps are present, when certain pathological features are found, or when the cells show high-grade abnormalities.

2.2 Serrated Polyps

Serrated polyps have glandular structures that appear saw-toothed when examined under a microscope. This group includes hyperplastic polyps, sessile serrated lesions, and traditional serrated adenomas. Most small hyperplastic polyps have a low risk of becoming cancerous. However, certain serrated polyps, particularly large polyps or those containing abnormal cells, may develop into colorectal cancer.

Some serrated polyps are flat and blend into the intestinal wall, making them more difficult to detect than raised or stalked polyps. Proper bowel preparation before a colonoscopy is therefore important for ensuring the quality and accuracy of the examination.

2.3 Inflammatory Polyps

Inflammatory polyps may occur in people with chronic inflammatory bowel diseases, such as ulcerative colitis or Crohn’s disease. The inflammatory polyps themselves may not be directly precancerous, but long-term inflammation of the colon may increase the risk of colorectal cancer. People with chronic inflammatory bowel disease should undergo examinations and follow-up according to the schedule recommended by their doctor, even if they do not have noticeable symptoms.

2.4 Hamartomatous Polyps

Hamartomatous polyps are less common and may sometimes be associated with inherited conditions, such as juvenile polyposis syndrome or Peutz-Jeghers syndrome. People who develop numerous polyps at a young age, or who have several family members with colon polyps or colorectal cancer, may need a detailed family history assessment and consideration of genetic testing.

3. Groups at Increased Risk of Colon Polyps

Colon polyps can occur in anyone, but the risk may be higher in older adults; people who have previously had polyps or colorectal cancer; and people with a parent, sibling, or child who has had colorectal cancer or high-risk colon polyps.

People with chronic inflammatory bowel disease and inherited conditions such as familial adenomatous polyposis, Lynch syndrome, and MUTYH-associated polyposis may also have a higher risk of numerous polyps and colorectal cancer. A person with a relevant family history should discuss risk assessment, screening, and possible genetic testing with a doctor.

Lifestyle or health factors that may be associated with increased risk include:

• Smoking
• Heavy alcohol consumption
• Being overweight or having obesity
• Physical inactivity
• Regular consumption of red or processed meat
• A diet low in fiber

Having one or more risk factors does not mean that a person will definitely develop colon polyps or cancer. At the same time, people without obvious risk factors may still develop colon polyps.

4. Causes and Factors Associated With Colon Polyp Formation

The exact cause of every case of colon polyps is not currently known. In general, polyps develop when cells in the intestinal lining divide and grow more than usual, eventually forming a growth. This process may be related to changes in genes that regulate cell growth, repair, and natural cell death.

Some genetic abnormalities may be inherited from a parent, while others may develop later in life and accumulate with age. Chronic inflammation of the intestine may also be involved. Lifestyle habits may contribute to long-term risk, including smoking, heavy alcohol consumption, physical inactivity, being overweight, and frequently eating large amounts of red or processed meat.

No single food or behavior causes a colon polyp to appear immediately. Risk usually results from a combination of factors, including age, genetics, general health, and lifestyle habits that accumulate over time.

5. Symptoms and Signs to Watch For

Most people with colon polyps do not experience symptoms, particularly when the polyps are small. However, some polyps may cause symptoms such as:

• Bright red blood on toilet paper or mixed with the stool
• Unusually dark or black stool
• Iron-deficiency anemia, fatigue, weakness, dizziness, or pale skin
• Persistent constipation or diarrhea, or changes in bowel movement frequency or stool pattern
• Abdominal pain, bloating, a feeling of incomplete bowel evacuation, or unintentional weight loss

These symptoms are not caused exclusively by colon polyps or colorectal cancer. They may also result from hemorrhoids, anal fissures, infections, or other gastrointestinal conditions. The cause should therefore not be diagnosed without a medical evaluation.

6. When to See a Doctor

A medical evaluation is recommended if there is blood in the stool, persistent changes in bowel habits, unexplained weight loss, or iron-deficiency anemia.

Blood in the stool should not automatically be assumed to come from hemorrhoids, especially if it occurs repeatedly or is accompanied by other unusual symptoms.

7. The Importance of Screening for Colon Polyps

Screening refers to testing for a disease or abnormality in people who do not yet have symptoms. It is particularly important for colon polyps because most people with polyps do not feel unwell. Detecting polyps before symptoms develop allows doctors to remove them and send them for examination before certain abnormal cells progress further.

7.1 Colonoscopy

A colonoscopy uses a flexible tube with a camera that is inserted through the rectum to examine the lining of the rectum and the entire colon. If a polyp is found, the doctor may be able to remove it or collect a tissue sample during the same procedure. Colonoscopy therefore plays a role in both diagnosis and treatment.

7.2 Stool Tests

Stool tests, such as the fecal immunochemical test (FIT), can be used to screen for colorectal cancer. However, they do not allow doctors to see polyps directly. If a stool test produces an abnormal result, a colonoscopy is generally required for further evaluation. A multitarget stool DNA test is another screening option that also requires a colonoscopy after an abnormal result.

7.3 CT Colonography

CT colonography, sometimes called a virtual colonoscopy, uses computed tomography to create images of the inside of the colon. It may help identify certain growths or polyps, but polyps cannot be removed during the examination. If an abnormality is detected, a conventional colonoscopy will still be required.

Many international guidelines recommend that adults at average risk who do not have symptoms begin colorectal cancer screening at around age 45. The appropriate screening method and interval should be based on age, general health, family history, and previous screening results. People at increased risk may need to begin screening earlier and undergo testing more frequently.

8. Treatment Options for Colon Polyps

The primary treatment for colon polyps is removal, which allows the tissue to be examined by a pathologist and may reduce the chance that a high-risk polyp will develop into cancer. Most polyps can be removed during a colonoscopy using a wire loop or another specialized instrument. This procedure is known as a polypectomy and usually does not require open abdominal surgery.

Large, flat, or difficult-to-reach polyps may require more advanced endoscopic techniques. Surgery on the colon may be considered when a polyp is very large, cannot be removed safely through a colonoscope, is in a difficult-to-access area, or contains cancer that has invaded deeper layers of the intestinal wall. The most suitable treatment depends on the size, location, and type of polyp, pathology results, underlying conditions, and overall health.

9. Care After Polyp Removal or Surgery

After a polyp is removed or surgery is performed, patients should carefully follow their doctor’s advice regarding diet, rest, physical activity, wound care, and medication use. People taking anticoagulants or antiplatelet medicines should not stop, restart, or adjust the dose on their own.

A small amount of blood in the stool may occur in some people after a polyp is removed. Contact a doctor promptly or seek emergency care for heavy or ongoing rectal bleeding, severe or worsening abdominal pain, fever, dizziness, fainting, unusual weakness, significant abdominal swelling, persistent vomiting, or an inability to pass stool or gas.

People who have had polyps removed may still develop new polyps. Follow-up colonoscopies should therefore be performed according to the recommended schedule, which varies according to polyp type, size, number, degree of abnormality, and the quality of the previous examination.

10. How to Reduce the Risk of Colon Polyps

There is currently no method that can completely prevent colon polyps, particularly those associated with age or inherited factors. However, healthy lifestyle choices may help reduce certain risk factors.

• Eat a varied diet containing vegetables, fruits, legumes, and whole grains; increase fiber gradually.
• Reduce red and processed meat, such as sausages, bacon, ham, and smoked meats.
• Exercise regularly and maintain an appropriate body weight.
• Avoid smoking and limit heavy alcohol consumption.
• Attend screening and follow-up examinations as advised by a doctor.

Aspirin, medicines, vitamins, herbal products, or dietary supplements should not be taken independently to prevent colon polyps. They may not be appropriate for everyone and may cause side effects, including bleeding in the stomach or intestines. Consult a doctor before starting them.

11. Summary

Colon polyps are growths that develop from the lining of the colon or rectum. Most are not cancerous and do not cause symptoms, but certain types may gradually develop into colorectal cancer over time. Screening allows polyps to be detected and removed before more serious abnormalities develop.

People within the recommended screening age range, those with a family history, those who have previously had polyps, or those with symptoms such as blood in the stool, anemia, or changes in bowel habits should consult a doctor for risk assessment and an appropriate screening method.

Prepared by: ภญ. ปุณยนุช อังคะนาวิน

References

1. National Institute of Diabetes and Digestive and Kidney Diseases. Colon Polyps
2. U.S. Preventive Services Task Force. Colorectal Cancer: Screening
3. American Society for Gastrointestinal Endoscopy. Understanding Polyps and Their Treatment