A 67-year-old woman with a family history of colon cancer is reluctant to undergo colonoscopy. What is the primary concern with stool testing?

• A. Low sensitivity
• B. Low specificity
• C. Risk of false-positive results
• D. Uncertain predictive values

Answer: (A)

Stool testing, particularly for colorectal cancer screening, is often used as a non-invasive alternative to colonoscopy. However, the primary concern regarding stool testing is its low sensitivity in comparison to the gold standard of colonoscopy. Although stool tests can effectively detect some cases of colorectal cancer and advanced adenomas, they may not identify all existing cancers, leading to false-negative results. This means there is a genuine risk that some individuals who have colorectal cancer could receive a negative result from stool testing, thereby missing the opportunity for early detection and potentially life-saving intervention.

While stool tests can have varying levels of specificity and may result in false-positive tests, the critical issue is that the sensitivity of these tests is not sufficient to confidently rule out disease when the risk is substantial, especially in patients with a familial history of colon cancer. Therefore, utilizing stool testing alone without follow-up colonoscopy might not adequately address the patient's risk profile.