Stool DNA Test
Overview
Stool DNA testing helps find early signs of colon cancer by analyzing a person’s stool sample. This method checks for certain DNA changes as well as hidden blood, both of which can be linked to precancerous growths or colorectal cancer.
Common options include multitarget stool DNA tests, such as Cologuard and Colosense, which detect a mix of unusual DNA markers and blood. Another option is the fecal immunochemical test (FIT), which looks for blood but does not check for DNA changes. The guaiac-based fecal occult blood test (gFOBT) is also available for blood detection.
| Test Name | Looks for DNA Changes | Detects Blood |
|---|---|---|
| Multitarget Stool DNA Test | Yes | Yes |
| FIT/FIT-DNA Combo | Sometimes | Yes |
| gFOBT | No | Yes |
If a stool DNA test result shows something abnormal, doctors may recommend further procedures, like a colonoscopy, for more information.
Reasons for Performing Stool DNA Testing
Stool DNA testing plays an important role in early colorectal cancer screening for individuals with no noticeable symptoms. The main purpose is to spot DNA changes and small traces of blood in stool that may be linked to the early development of colon or rectal cancer. The detection of these markers helps catch problems before symptoms start, which allows early treatment and can reduce cancer death rates.
This screening method targets people at average risk of colon cancer, offering a non-invasive way to check for abnormal cell growths, called polyps, that might later become cancer. It is typically not recommended for those with a history of colon cancer, polyps, or conditions like ulcerative colitis.
| Feature | Description |
|---|---|
| Main Target | Precancerous polyps & colorectal cancer |
| Test Type | Non-invasive, stool-based |
| Best For | Average-risk individuals |
| Follow-Up | Positive results → colonoscopy |
| Screening Interval | About every 3 years |
Other common tests for colon cancer screening include colonoscopy and CT colonography (sometimes called virtual colonoscopy).
Possible Drawbacks
The stool DNA test carries some risks. It may give a false-positive result, meaning it suggests cancer is present when it is not. It can also give a false-negative result, where the test misses existing cancer. These results can lead to extra testing, such as a colonoscopy.
Individuals with inflammatory bowel disease or certain genetic syndromes—like Lynch syndrome or familial adenomatous polyposis—may need different testing methods.
| Issue | Details |
|---|---|
| Test Accuracy | False-positives and false-negatives |
| Need for Further Testing | Possible follow-up with colonoscopy |
| FDA Approval | For average-risk people, age 45+ |
| Insurance Coverage | May not cover all test cases |
Anyone at higher risk, such as those with Crohn’s disease, should discuss the best screening option with their provider.
Getting Ready for the Test
You do not need to take special steps before a stool DNA test. You can eat, drink, and take your usual medications. Bowel preparation is not required. A health care provider gives you the kit and instructions. This process is straightforward, with no changes to daily habits needed.
What Happens During the Process
You collect a stool sample at home using a test kit. The kit includes a container that fits on the toilet, making it easier to collect the sample. After collecting the sample, you add a preservative solution and seal the container.
You then return the sample by mail or drop it off at a health care provider’s office. Lab specialists check for DNA changes, biomarkers, and traces of hidden blood or occult blood in the stool. If results show abnormal findings, doctors usually recommend a follow-up colonoscopy.
Key Points
- Only one stool sample is needed.
- At-home collection for convenience.
- The test looks for blood in stool and DNA biomarkers.
Stool DNA Test Outcomes
The stool DNA test can give either a negative or positive result.
- A negative result means the lab found no abnormal DNA or blood in the stool. People who get a negative result often repeat the test every three years.
- A positive result signals that the test found DNA changes or blood in the sample. This may suggest the presence of colon polyps, advanced adenomas, or even precancerous polyps.
Further Steps
- If the test is positive, doctors usually suggest a colonoscopy to check for colorectal polyps or cancer.
- Markers such as KRAS, NDRG4, and BMP3 may be involved in detecting changes.
| Result | Meaning | Next Steps |
|---|---|---|
| Negative | No abnormal DNA/blood detected | Test again in 3 years |
| Positive | DNA changes or blood present | Colonoscopy is recommended |
