This study investigates the use of blood tests to detect the return of colorectal cancer. Colorectal cancer, or CRC, is a type of cancer that affects the colon or rectum. The study compares two tests: Colvera, which looks for specific DNA changes in the blood, and the CEA test, which measures a protein often found in higher levels in cancer patients. The goal is to see which test is better at identifying if the cancer has come back in patients who have already been treated for CRC and are in remission, meaning their cancer is not currently active.

Participants in the study will have their blood drawn to check for certain DNA changes and protein levels. These results will be compared to a standard reference to determine their accuracy. This study does not involve any new treatments or medications, but rather focuses on analyzing blood samples to evaluate the effectiveness of these tests in monitoring cancer recurrence.

• Who can participate: Adults who have been treated for stage II or III colorectal cancer and are currently in remission can participate. They must have had a CT scan in the last four weeks showing whether or not their cancer has returned. Participants must be willing to provide a blood sample.
• Study details: Participants will provide a blood sample to test for DNA changes and protein levels related to colorectal cancer. No treatments or medications are involved in this study, only blood sample collection for test comparison.