A colon adenoma is a benign growth, also known as a polyp, that forms on the inner lining of the colon or rectum. While these growths are not cancerous, they are considered precancerous. This is because adenomas have the potential to develop into colorectal cancer over an extended period if they are not detected and removed.
Causes and Risk Factors
The development of colon adenomas is influenced by a combination of factors, some of which cannot be changed. Age is a primary non-modifiable risk factor, with the likelihood of developing adenomas increasing significantly after the age of 50. A personal or family history of colorectal polyps or cancer also elevates an individual’s risk. Certain inherited genetic conditions, such as Familial Adenomatous Polyposis (FAP), create a strong predisposition for developing numerous adenomas, often at a much younger age.
Other risk factors are related to lifestyle choices and are considered modifiable. Diets that are high in processed and red meats and low in fiber have been linked to an increased risk of adenoma formation. Similarly, lifestyle habits such as smoking, heavy alcohol consumption, physical inactivity, and obesity are associated with a greater chance of developing these polyps. The presence of type 2 diabetes is another condition that raises the risk of developing adenomas.
Detection and Diagnosis
In most cases, colon adenomas do not produce any noticeable symptoms, which is why they are often discovered during routine health screenings. When symptoms do occur, they might include rectal bleeding, changes in bowel habits like constipation or diarrhea, or abdominal pain, but these are not specific to polyps.
The primary and most definitive method for both detecting and diagnosing colon adenomas is a colonoscopy. This procedure involves a physician using a long, thin, flexible tube equipped with a light and camera to visually examine the entire length of the colon and rectum. It allows for direct inspection of the colon’s lining, enabling the identification of polyps that might otherwise go unnoticed. While other screening methods like stool-based tests exist, a colonoscopy is required to confirm the presence of an adenoma and allows for its immediate removal.
Removal and Follow-Up
When an adenoma is identified during a colonoscopy, it is typically removed in the same session through a procedure called a polypectomy. This is most often done by passing a wire loop or forceps through the colonoscope to snare and detach the growth from the colon wall. The removed tissue is then sent to a pathology lab for detailed analysis.
The pathologist’s report will detail the number, size, and specific type of the adenomas found. Adenomas larger than one centimeter or those with certain cellular features, known as villous or tubulovillous patterns, are associated with a higher risk of progressing to cancer. Based on these findings, a personalized follow-up plan is created. This surveillance plan dictates the schedule for future colonoscopies to monitor for any new polyp development.
The recommended interval for this surveillance varies. For patients with only one or two small (less than 10mm) tubular adenomas, a repeat colonoscopy may be suggested in 7 to 10 years. However, for individuals with three or more adenomas, a large adenoma, or one with higher-risk histology, a shorter interval of three years is often recommended.