Observational Cross-reactivity Study for Colorectal Cancer Diagnosis

This study evaluates whether a diagnostic blood test for colorectal cancer also reacts to other cancers or gastrointestinal diseases — called "cross-reactivity." By testing blood from people with other GI conditions (but not colorectal cancer), researchers can understand whether the test might produce false positive results. **You may be eligible if...** - You are older than 18 - You have been diagnosed with only one type of cancer that is NOT colorectal cancer, or you have a gastrointestinal disease (but not colorectal cancer) - You can understand the study information and sign a consent form **You may NOT be eligible if...** - You have received chemotherapy or radiation therapy previously - You have two or more different cancer diagnoses - You have a condition that might interfere with blood test results Talk to your doctor to see if this trial is right for you.