Colorectal Cancer Screening via Stool Analysis
What is Analyzed in a Stool Test?
1. Fecal Occult Blood Test (FOB)
This is a simple and affordable stool test with results available within 1 hour. No fasting is required. However, it has limitations: its sensitivity for detecting pre-cancerous stages is relatively low (<65%), and "False Negatives" (where blood is present but the test result is negative) can occur if the patient is not actively bleeding at the time of the sample.
2. Transferrin Test
Transferrin is a protein found in the blood. If detected in the stool in higher-than-normal amounts, it indicates potential bleeding within the gastrointestinal tract.
3. Calprotectin Test
This is a protein marker excreted in the stool when there is inflammation in the digestive system. High levels clearly indicate intestinal inflammation, often found in patients with Inflammatory Bowel Disease (IBD), intestinal infections, or colorectal cancer.
4. Lactoferrin Test
Similar to Calprotectin, high levels of this blood protein in the stool serve as a reliable indicator of gastrointestinal inflammation.
Combining the FOB test with Transferrin, Calprotectin, and Lactoferrin analysis is known as an Inflammation Screening or the Stool Quad Test. This combination increases the sensitivity for detecting pre-cancerous polyps to 67–76%. Early detection allows for minimally invasive endoscopic surgery, resulting in smaller wounds and faster recovery. However, False Negatives may still occur in patients using Non-Steroidal Anti-Inflammatory Drugs (NSAIDs).
What Diseases Can It Screen For?
The test can help identify peptic ulcers, infectious or ulcerative colitis, diverticulitis, hemorrhoids, polyps, non-cancerous tumors, and colorectal or anal cancer.
Who Should Get Tested?
- Individuals aged 40 and older.
- Those experiencing regular bloating, chronic constipation, or constipation alternating with diarrhea, or stools containing mucus/blood.
- Frequent abdominal pain, indigestion, or cramping.
- Patients with chronic inflammatory bowel conditions.
- A noticeable narrowing of stool size (pencil-thin stools).
- Unexplained weight loss or anemia.
- Individuals with a family history of polyps or colorectal cancer.
- Anyone wishing to screen for gastrointestinal abnormalities as part of an annual health check-up.
Interpreting the Results
- Negative Result: No blood or inflammatory markers were detected. However, this does not 100% guarantee the absence of GI diseases or cancer. Annual screening is recommended, and any unusual symptoms should be reported to a doctor immediately.
- Positive Result: Indicators were found in the stool. This can be caused by various factors. The doctor may recommend further investigation via Gastroscopy (EGD) or Colonoscopy to identify the exact cause and begin treatment promptly.
