Tubular adenoma of the colon

A tubular adenoma is a type of colon polyp that forms on the inner lining of the large intestine. It is the most common type of adenoma found during colonoscopy and is considered precancerous. This means it can slowly change into colon cancer over time if it’s not removed.

About 1 in 3 adults over age 50 will develop at least one adenoma in their lives. Adenomas are grouped by how their cells are arranged under a microscope. Tubular adenomas have round, tube-shaped glands and carry the lowest cancer risk. Villous adenomas have longer, fingerlike shapes and a higher risk, while tubulovillous adenomas have features of both.

All adenomas show dysplasia, meaning the cells grow in an irregular pattern. Low-grade dysplasia shows early change, while high-grade dysplasia means an area has more-serious precancerous growth and requires more-frequent monitoring.

A tubular adenoma is benign, meaning it is not cancer, but over time it has the potential to develop into a type of cancer called adenocarcinoma. Because of this, it should be removed when found and monitored through follow-up colonoscopy.

Types of polyps

There are many different types of polyps found during a colonoscopy, and the names can sometimes be confusing. An adenoma is one type of colon polyp, which means that all adenomas are polyps. However, not all polyps are adenomas. Each type has its own features and level of cancer risk.

Most tubular adenomas do not cause symptoms. They usually grow very slowly and are often discovered during a routine screening colonoscopy before they cause any problems. Most people with tubular adenomas feel well and have no warning signs. Finding and removing these adenomas early is one of the main reasons colon cancer screening is so effective.

Though tubular adenomas usually do not cause symptoms, certain changes can be signs that require prompt medical evaluation to rule out colon cancer. These include:

• Small amounts of blood in the stool or on toilet paper.
• Changes in bowel habits, such as new constipation or diarrhea.
• Abdominal pain or discomfort.
• Changes in the shape or size of the stool.

The exact cause of tubular adenomas is not fully known, but they develop when the lining of the colon begins to grow faster than usual. Over time, this extra growth can form a polyp. Most tubular adenomas start as tiny clusters of cells that gradually enlarge over many years.

Anyone can develop a tubular adenoma or other types of polyps, but certain factors make them more likely to occur:

• Age. Most people with colon polyps are 50 or older.
• Intestinal conditions. Having inflammatory bowel disease, such as ulcerative colitis or Crohn’s disease, raises the overall risk of getting polyps and colorectal cancer.
• Family history. Having a parent, sibling or child with advanced colon polyps increases the risk of getting them. An example of an advanced colon polyp is one that is 10 millimeters (mm) in diameter or larger. If many family members have them, the risk is even greater.
• Personal history of colorectal polyps. Previous polyps are a risk factor for forming new polyps.
• Smoking and excess alcohol use. Studies show that people who have three or more alcoholic drinks a day have an increased risk of getting colon polyps. Alcohol intake combined with smoking also appears to increase the risk.
• Diabetes. Having diabetes increases polyp risk by 50% among all age groups.
• Obesity, lack of exercise and a less healthy diet. The risk of colon polyps increases for people who are overweight, eat a less healthy diet and don’t exercise regularly.
• Race. In the U.S., Native American and Alaska Native people have the highest rates of colorectal cancer, followed by African American men and women. Ashkenazi Jews have one of the highest colorectal cancer risks of any ethnic group in the world.
• Having an inherited syndrome. Hereditary conditions are health concerns passed down from parents. Rarely, people inherit gene changes that cause colon polyps to form and increase the risk of colorectal cancer. Conditions commonly associated with colorectal cancer include Lynch syndrome and familial adenomatous polyposis (FAP).

Having one or more of these risk factors does not mean a person will definitely develop a tubular adenoma, but it may increase the importance of regular colonoscopy screening and healthy lifestyle habits.

Most tubular adenomas are found during routine screening, such as colonoscopy, rather than because of symptoms. During colonoscopy, a healthcare professional uses a long, flexible tube attached to a video camera. This allows the health professional to view the whole colon and rectum on a video monitor.

If the healthcare professional sees any small growths, called polyps, they can often be removed right then. This is important because while most polyps are not cancerous, some can develop into cancer over time.

Tubular adenomas are characterized by the specific structure, which looks like branching tubelike glands under the microscope. Sometimes during the colonoscopy, the healthcare team can see specific patterns on the surface of the polyp using special imaging techniques. For example, brown slits within the glands can suggest the polyp might be a tubular adenoma.

While a colonoscopy helps find and remove these polyps, the final diagnosis is made by looking at the tissue under a microscope. This process helps ensure you receive the right treatment and follow-up monitoring.

Understanding your pathology report

When a polyp is removed, it’s sent to a lab for a specialist, called a pathologist, to examine under a microscope. This exam is called histopathology. It’s the most important step for a definitive diagnosis.

Common terms you might see on a pathology report include:

• Type of polyp. Your report may say tubular adenoma. That means the growth is not cancerous, also called benign. But because it has the potential to develop into cancer over time if not removed, it is considered precancerous.
• Size and location. The report usually states how large the polyp is and where in the colon or rectum it was found.
• Microscopic, called histologic, findings. This describes what the tissue looks like under the microscope. For example, tubular adenomas have a tubelike gland structure.
• Dysplasia grade. If the report says low-grade dysplasia, this means that the cells show early or mild changes. The risk of cancer is very low when the polyp is completely removed. If it says high-grade or focal high-grade dysplasia, this means an area of the polyp shows more-advanced precancerous change, but it is not cancer. Complete removal gets rid of the risk of the polyp turning into cancer.
• Margin status. If the polyp was removed in one piece, the report may say whether the edges, called margins, of the tissue are free of unusual cells. If there are no suspicious cells, your report will say negative margin. If there are remaining suspicious cells, it will say positive margin. This helps assess whether the removal was complete.
• High-risk features. The report may note whether the polyp had features that raise cancer risk, such as larger size, multiple adenomas, any villous (fingerlike) features or presence of high-grade dysplasia.
• Interpretation and follow-up recommendation. Some reports include a summary or note on what the findings mean for you and when you should return for another colonoscopy or follow-up.

When to repeat colonoscopy

After a tubular adenoma is removed, your healthcare team will likely recommend follow-up colonoscopies based on the number, size and features of the polyps.

The main treatment for tubular adenomas is polypectomy, which means removing the adenoma during a colonoscopy. During this procedure, a healthcare professional guides a long, flexible tube called an endoscope — equipped with a light, camera and tiny surgical tools — through the colon to see and remove the growth. A wire loop, called a snare, is used to cut the adenoma away. This is a quick, generally painless procedure performed under sedation.

• Small adenomas can often be removed in one piece.
• Larger adenomas may be taken out in several pieces, called piecemeal resection or fragments.
• Very large or difficult-to-reach adenomas sometimes require a second colonoscopy or, rarely, surgery if they cannot be removed safely with an endoscope.

Once removed, the tissue is sent to a lab to confirm that the entire polyp was taken out and to look for any areas with cell changes, called dysplasia, or other high-risk features.

Can tubular adenomas come back?

If a polyp is not completely removed — for example, if polyp cells or tissue are inadvertently left behind — the polyp can regrow in the same location. After removal of large polyps, especially by piecemeal approach, a second colonoscopy may be scheduled within the next 3 to 6 months to carefully reinspect the area to make sure none was left behind.

After complete removal, the same polyp does not grow back. But new adenomas can form over time. This is why follow-up colonoscopies are so important. Following the schedule your healthcare professional recommends helps find and remove any new polyps before they can cause harm.

When does a tubular adenoma become cancer?

A tubular adenoma becomes cancer only if its cells continue to grow and change over many years without being removed. The risk is very low once a polyp has been taken out completely. Adenomas that are large, contain high-grade dysplasia or have villous features are more likely to progress if left untreated.

Stool-based colorectal cancer screening tests such as multitarget stool DNA testing (Cologuard) can identify many large and most high-grade polyps. These tests do not by themselves indicate a polyp or cancer when positive. A colonoscopy must be performed to evaluate anyone with a positive stool screening test. Regular colon cancer screening and complete removal of all adenomas are the best ways to prevent colon cancer from developing.

If you’ve been told you have a tubular adenoma, you’ll likely be referred to specialists who evaluate and treat colon polyps. You might meet with:

• A doctor who treats digestive diseases, called a gastroenterologist.
• A doctor who performs colonoscopy or colon surgery, such as a colorectal surgeon.
• A doctor who reviews tissue samples under a microscope, called a pathologist.

Here’s some information to help you get ready for your appointment.

What you can do

Ask a trusted family member or friend to go with you. Having another person there can help you remember what the healthcare team says and provide emotional support.

Make a list of:

• Your symptoms, if you have any, and when they began.
• Key medical information, including other health conditions and any history of colon polyps or colon cancer in your family.
• All medicines, vitamins or supplements you take, including doses.
• Questions you’d like to ask your healthcare team.

Questions to ask your doctor

Some basic questions to consider include:

• Where in my colon was the tubular adenoma found?
• How large was the adenoma, and was it completely removed?
• Did the pathology report show low-grade or high-grade dysplasia?
• How often should I have follow-up colonoscopies?
• What is my risk of developing new adenomas or colon cancer?
• Are there changes I can make to lower my risk, such as diet or lifestyle habits?
• Will I need to see a specialist again before my next screening?
• Can I have a copy of my pathology report for my records?
• Are there any educational materials or websites you recommend for learning more?

What to expect from your doctor

Be prepared to answer some basic questions, such as:

• Have you ever had colon polyps before?
• Do you have a family history of colon cancer or polyps?
• Have you noticed any blood in your stool or other bowel changes?
• Have you ever had a colonoscopy or stool test before this one?
• Do you have any chronic health conditions, such as inflammatory bowel disease?

Being ready to discuss your questions and history will help you and your healthcare team make the best plan for follow-up and long-term prevention.