Stool DNA Test

The stool DNA test, also known as the stool DNA screening test or Cologuard, is a non-invasive diagnostic tool used to detect colon cancer and precancerous polyps in the colon.

How it Works

The test analyzes a stool sample for abnormal DNA from colon cancer cells or precancerous polyps. The test looks for specific genetic mutations that are commonly found in colon cancer and precancerous polyps, as well as blood in the stool, which can be a sign of colon cancer.

What the Test Detects

The stool DNA test detects:

• Abnormal DNA from colon cancer cells or precancerous polyps
• Blood in the stool (hemoglobin)
• Methylated genes, which are genes that have been altered by the addition of a methyl group, a common feature of colon cancer cells

How to Prepare for the Test

To prepare for the test, patients typically:

• Avoid certain medications, such as aspirin and ibuprofen, that can interfere with the test results
• Avoid eating certain foods, such as red meat, that can affect the test results
• Collect a stool sample using a special kit provided by the doctor or laboratory

Interpreting Test Results

The test results are typically reported as:

• Positive: abnormal DNA or blood is detected in the stool, which may indicate colon cancer or precancerous polyps
• Negative: no abnormal DNA or blood is detected in the stool, which suggests that colon cancer or precancerous polyps are unlikely
• Uncertain or inconclusive: the test results are unclear or cannot be interpreted

Limitations and Risks

The stool DNA test has several limitations and risks, including:

• False positive results: the test may detect abnormal DNA or blood in the stool when no colon cancer or precancerous polyps are present
• False negative results: the test may fail to detect colon cancer or precancerous polyps when they are present
• The test does not detect all types of colon cancer, such as serrated polyps

Recommendations and Guidelines

The American Cancer Society recommends that adults aged 45 to 75 years undergo regular screening for colon cancer using one of several tests, including the stool DNA test. The US Preventive Services Task Force also recommends screening for colon cancer in adults aged 50 to 75 years.

Frequently Asked Questions (FAQs)

What is a Stool DNA test?
A non-invasive screening test for colon cancer that detects DNA mutations in stool.

How is the Stool DNA test performed?
A stool sample is collected and sent to a lab for analysis of DNA biomarkers.

What does the Stool DNA test screen for?
Colon cancer, precancerous polyps, and other gastrointestinal conditions.

Is the Stool DNA test used for diagnostic purposes?
Typically used for screening, not diagnosis, with follow-up testing needed for positive results.

How accurate is the Stool DNA test?
Generally considered to be around 90-92% sensitive for colon cancer detection.

Are there any preparation requirements for the Stool DNA test?
Some tests may require a specific diet or avoidance of certain medications before sample collection.

Can the Stool DNA test detect other conditions besides colon cancer?
May also detect other gastrointestinal conditions, such as inflammatory bowel disease.

How often should the Stool DNA test be performed?
Typically recommended every 3 years for average-risk individuals aged 50-85.

Is the Stool DNA test covered by insurance?
Often covered by insurance, but coverage may vary depending on individual policies and risk factors.

What are the advantages of the Stool DNA test?
Non-invasive, relatively easy to perform, and may be more comfortable for patients than other screening methods.