Descripción general
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.
| Polyp type |
Microscopic appearance |
Precancerous: Yes or No |
Cancer risk |
Notes |
| Tubular adenoma |
Tube-shaped glands |
Yes |
Low |
This is the most common adenoma. It grows slowly and has the lowest risk of becoming cancer among adenoma types. |
| Villous adenoma |
Long, fingerlike projections |
Yes |
High |
This is less common than tubular adenoma, but it carries the highest chance of becoming cancer if left untreated. |
| Tubulovillous adenoma |
Mix of tubelike and fingerlike glands |
Yes |
High |
This type has features of both tubular and villous adenomas. Its risk of turning into cancer is high if it is not removed. |
| Serrated adenoma |
Saw-toothed gland pattern |
Yes |
Variable |
This polyp follows a different growth pathway. It is not a tubular adenoma but is still considered precancerous. |
| Hyperplastic polyp |
Flat or saw-toothed surface |
No |
Very low |
This type of polyp is common, especially in the rectum and sigmoid colon. It is usually harmless and not considered precancerous. |
| Inflammatory polyp |
Irregular, inflamed tissue |
No |
None |
This polyp forms in areas of long-term inflammation, such as in people with inflammatory bowel disease. It is not a true adenoma and does not turn into cancer. |
| Hamartomatous polyp |
Disorganized normal tissue |
Sometimes |
Slightly increased if there are multiple polyps or they are caused by a genetic condition. |
This polyp is usually not cancerous but can appear in people with certain inherited syndromes. |
Síntomas
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.
Causas
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.
Factores de riesgo
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.