Cologuard offers a non-invasive option for colorectal cancer screening, providing a convenient alternative to traditional methods. Many individuals wonder if growths like polyps can lead to a positive Cologuard test result. This article explains Cologuard’s detection capabilities, clarifies what a positive result signifies, and outlines the necessary steps to take if you receive such a result.
What Cologuard Is and How It Detects Markers
Cologuard is a stool DNA test designed for colorectal cancer screening in individuals at average risk, typically those aged 45 and older. It analyzes a stool sample for specific biological markers associated with colorectal cancer and precancerous growths. This non-invasive method can be performed at home, offering a convenient way to screen for potential issues.
Cologuard looks for two main types of markers. It identifies abnormal DNA mutations that are shed from cancerous or precancerous cells in the colon or rectum. These include specific genetic alterations in genes like BMP3, NDRG4, and KRAS, as well as beta-actin. Additionally, Cologuard detects occult hemoglobin, which is microscopic blood in the stool. The presence of either abnormal DNA or blood markers suggests the need for further investigation, as the test screens for potential issues rather than providing a direct diagnosis.
Polyps and Why Cologuard Detects Them
Polyps are growths that can form on the inner lining of the colon or rectum. While many polyps are harmless, some types, particularly adenomatous polyps, have the potential to develop into colorectal cancer over time. These adenomatous polyps are considered precancerous and are a primary focus of colorectal cancer screening efforts.
Cologuard is designed to detect polyps that are more likely to be precancerous or cancerous. This detection occurs because these growths, particularly adenomas, can shed abnormal DNA into the stool as cells naturally slough off the colon lining. The DNA markers Cologuard looks for are the genetic changes within these shedding cells. Furthermore, some polyps, especially larger ones or those with certain characteristics, can bleed intermittently, releasing tiny amounts of blood into the stool. Cologuard’s ability to detect this microscopic hemoglobin contributes to its effectiveness in identifying potential issues related to these growths. Therefore, a positive Cologuard result may indicate the presence of these precancerous polyps or early-stage cancers due to the abnormal DNA and/or blood they release.
What a Positive Cologuard Result Indicates
A positive Cologuard test result does not mean an individual has cancer. Instead, it indicates that the test detected abnormal DNA markers or occult blood in the stool sample, suggesting the need for additional medical evaluation. Cologuard is a screening tool, not a diagnostic one, meaning its purpose is to identify individuals who might have precancerous polyps or cancer and who should undergo further testing.
A positive result signals that there are biological clues in the stool that warrant a closer look at the colon. While it can suggest the presence of precancerous polyps or colorectal cancer, other factors can also lead to a positive result. For instance, benign conditions, such as hemorrhoids, can cause blood in the stool and trigger a positive finding. A percentage of individuals without colorectal cancer or advanced adenomas received a positive result, which is known as a false positive. This outcome underscores that a positive Cologuard test simply means “further investigation is needed” to determine the exact cause of the detected markers.
Essential Actions After a Positive Test
Following a positive Cologuard result, the immediate action is to schedule a diagnostic colonoscopy. This procedure is the next step to investigate the source of the abnormal markers detected by the Cologuard test. A colonoscopy allows a healthcare provider to visualize the entire colon and rectum, identifying any polyps, abnormal growths, or suspicious areas.
During a colonoscopy, any polyps found can often be removed immediately, preventing them from potentially developing into cancer. Tissue samples can also be taken for biopsy to determine if any abnormalities are cancerous or precancerous. This follow-up colonoscopy is considered a part of the screening process, ensuring that any detected issues are accurately diagnosed and addressed promptly. Consulting with a healthcare provider, such as a gastroenterologist, is important to discuss the Cologuard results and arrange the necessary colonoscopy.