A colonoscopy allows medical professionals to examine the inner lining of the large intestine. During this examination, doctors often discover growths called polyps. A common question is whether a doctor can definitively determine if a polyp is cancerous during the procedure itself. This article explores the nature of colon polyps and the diagnostic process to clarify how malignancy is confirmed.
What Are Colon Polyps?
Colon polyps are abnormal tissue growths that form on the inner lining of the colon or rectum. While many are harmless, some types have the potential to develop into cancer over time. Healthcare providers typically remove polyps when found during a colonoscopy to prevent this progression.
Polyps are broadly classified into neoplastic and non-neoplastic types based on their potential to become cancerous. Adenomatous polyps, also known as adenomas, are the most common neoplastic type. These include tubular, villous, and tubulovillous adenomas, with villous adenomas carrying a higher risk of malignancy.
Conversely, hyperplastic polyps are generally non-neoplastic and are typically not considered precancerous, especially when small and located in the lower colon. Another type, sessile serrated lesions, can also become cancerous and may be challenging to detect due to their flat shape. Polyps can also be described by their physical appearance: “pedunculated” (mushroom-like with a stalk) or “sessile” (flat against the colon wall).
Visual Clues During Colonoscopy
While a gastroenterologist can identify polyps during a colonoscopy, they cannot definitively determine if a polyp is cancerous by visual inspection alone. The visual assessment provides important clues, but a conclusive diagnosis requires further analysis.
Doctors observe several visual characteristics that might raise suspicion during the procedure. These include the polyp’s size, shape, and surface irregularities. For instance, larger polyps, particularly those greater than 1 centimeter in diameter, have a higher risk of containing cancerous cells.
Other indicators that might suggest a higher risk include a flat or depressed appearance, or unusual color and vascular patterns on the polyp’s surface. However, even polyps that appear suspicious often turn out to be benign upon microscopic examination. Conversely, some seemingly harmless polyps may harbor early cancerous changes.
How Polyps Are Diagnosed
The definitive diagnosis of a colon polyp is made through a process called a polypectomy or biopsy, followed by a microscopic examination. When a polyp is identified during a colonoscopy, it is typically removed using special tools passed through the colonoscope. This removal process, known as a polypectomy, is usually painless.
The removed tissue is then sent to a pathology laboratory for detailed analysis. Here, a specialized doctor called a pathologist examines the tissue under a microscope. This microscopic analysis allows the pathologist to identify the specific type of polyp and assess for the presence of abnormal cells, known as dysplasia, or cancer cells.
The pathologist’s report will classify the polyp as benign (non-cancerous), precancerous (showing dysplasia, which can be low-grade or high-grade), or cancerous. This detailed examination is the only way to confirm whether a polyp is malignant. The information from this report is crucial for determining the appropriate next steps in a patient’s care.
After the Diagnosis
Once the pathology report is available, the doctor will review the findings with the patient, explaining the type of polyp found and whether it showed any signs of cancer. The report details the polyp’s characteristics, such as its size, type, and the presence or absence of dysplasia.
Based on the pathology results, a personalized follow-up plan is developed. If benign polyps were removed, or low-risk adenomas, the next colonoscopy might be recommended in several years, potentially five to ten years. For those with high-risk adenomas, such as multiple polyps, larger polyps (over 1 cm), or those with high-grade dysplasia, more frequent surveillance colonoscopies are typically advised, often within three years.
If cancer is diagnosed within the polyp, further evaluation and treatment options will be discussed. This may involve additional imaging tests to determine if the cancer has spread, and a multidisciplinary team of specialists will then outline a comprehensive treatment plan, which could include surgery or other therapies.