Adenomatous polyps, or adenomas, are a type of poly that can turn into cancer. Treatment typically involves surgical removal.

Polyps are common in older adults, with colorectal polyps occurring in 30% of adults over the age of 50 years in the United States. Different types of colon polyps can include adenomas and hyperplastic polyps.

While most adenomas are harmless, some can develop into cancer. For this reason, some people may refer to adenomas as a precancerous condition.

Almost all colorectal cancer is due to polyps. Therefore, if a person has precancerous polyps, a doctor will often remove them before cancer can develop.

In this article, we will discuss what adenomas are, how a doctor may diagnose them, and what treatment options are available.

A histological slide of an adenoma.Share on Pinterest
Photo editing by Stephen Kelly; David A Litman/Shutterstock

Adenomatous polyps, often known as adenomas, are a type of polyps that can turn into cancer.

Adenomas may form in the mucous membrane of the lining in the large intestine, making them colon polyps. Another type of adenoma is gastric polyps, which form in the lining of the stomach.

Adenomas often appear in several growth patterns. The two most common patterns are tubular and villous.

Tubular adenomas tend to be small in size and grow in a tubular shape. They are usually less than half an inch long. The characteristic feature of villous adenomas is finger- or leaf-like projections coming out of the adenoma.

Some adenomas may develop a mixture of both villous and tubular growth patterns. Experts refer to these as tubulovillous adenomas.

Adenomas with a villous growth pattern are more likely to have cancers grow inside them. Cancer is also more likely to develop in larger adenomas.

Anyone can develop adenomatous polyps. However, there are some factors that increase a person’s risk of developing them.

For instance, people are more likely to receive a diagnosis of colorectal cancer if they:

Other variables that may also increase the likelihood of developing this type of cancer include:

People with colon polyps often experience no symptoms. Doctors typically discover the polyps during routine screenings or tests or during tests for other conditions.

However, symptoms can sometimes arise. A person with colon polyps can experience:

A doctor will often detect adenomas during regular screening for colon cancer.

If a doctor suspects that polyps are present, they may assess a person’s risk factors and perform a physical exam before any screening takes place.

If further tests are necessary, they will often use one of a number of screening methods to detect the polyps.

It is important that a doctor finds adenomas early, as this can reduce the risk of complications such as cancer.

Different screening methods may include:

  • Colonoscopy: This examination involves using a camera tube. A doctor inserts the tube through the rectum and into the colon to closely inspect it. They may also remove polyps or carry out a biopsy, which involves removing a sample of tissue to send to a laboratory for examination.
  • Virtual colonoscopy: This is a minimally invasive test during which a doctor will use a CT scan, X-ray, or MRI scan to examine the colon. If the doctor discovers any polyps, a regular colonoscopy will be necessary to remove them.
  • Flexible sigmoidoscopy: This method is similar to a colonoscopy but uses a smaller lighted tube. The doctor inserts this through the rectum to examine it along with the last third of the colon. If the doctor finds polyps, then a regular colonoscopy will be necessary to remove them.
  • Stool test: A doctor may check for blood in a person’s stool. During this exam, they may also test the DNA in the stool. If certain results arise, the doctor may then carry out a colonoscopy to investigate further.

If a person has colon polyps, a doctor will usually remove them during a polypectomy.

As part of this procedure, a doctor passes the colonoscope through the rectum and into the colon. The colonoscope has a wire attached to it, which either burns off or cuts the polyp free. Both of these methods cause little to no pain.

In rare instances when the polyp is difficult to remove, a doctor may carry out a laparoscopy. This involves making a small incision in the abdomen or pelvis. The doctor then uses an instrument called a laparoscope to remove the polyps.

A laparoscope is slender, which means that all that is necessary to carry out the procedure is a very small incision. Once the doctor has removed the polyp, they will usually send it to a pathologist, who will test it for cancer.

If a person has a more severe condition, such as colon cancer, they may require surgery.

During this procedure, a surgeon will remove either part or all of the person’s colon and rectum. The severity of the cancer and the presence of other issues will help the doctor determine how much of the colon to remove.

If a person has familial adenomatous polyposis (FAP) alongside colon cancer, the doctor may decide to remove the entire colon. FAP is a rare inherited condition that causes hundreds of polyps to appear and can cause colon cancer to develop.

Adenomas may be harmless, but they may also develop into cancer.

The presence of adenomas increases a person’s risk of having colorectal cancer. However, not all adenomas precede cancer.

Research suggests that adenomas with a villous growth patterns are more likely to turn into cancer.

A 2014 review outlines the role that size played in the risk of cancer. According to the review, adenomas that are 5 millimeters or less had a very low risk of leading to cancer.

The same review also states that adenomas between 1.5 and 3.5 centimeters had a 19–43% likelihood of developing into cancer.

A person should seek guidance from a healthcare professional if they:

  • have a family history of colon polyps or colon cancer
  • are frequently experiencing rectal pain or the sensation of needing to have a bowel movement
  • are experiencing bleeding from the rectum
  • have blood in their stools
  • are experiencing anemia

Adenomatous polyps are typically benign growths that develop inside the tissues of different organs, such as the colon.

While many of these growths are harmless, they can be precancerous. This means they could develop into cancer.

If a doctor discovers these polyps, they will often remove them using polypectomy or surgery. They will then send the removed polyps to a pathologist for a biopsy to see whether cancer is present.

If they detect cancer, the doctor will decide on a most suitable treatment plan.