This study is trying to find the best way to detect if colorectal cancer (CRC) comes back after surgery. It uses two types of blood tests: the Haystack and the Signatera assays. An assay is a kind of test. These tests look for minimal residual disease (MRD), which means tiny amounts of cancer that might still be in the body after treatment. Right now, doctors use the Signatera test, but it might not catch cancer early enough. The Haystack test might be better at finding cancer sooner.

Key Points:

• The study will last for 5 years, with regular blood tests (every 3 months for the first 2 years and every 6 months for the next 3 years).
• Participants should be 18 or older and have stage II-IV CRC that can be removed by surgery.
• Participants must be willing to give blood samples regularly and allow access to their tissue samples.

This study could help doctors find cancer earlier, possibly improving treatment results. Participants will need to visit the hospital for regular blood tests, but it might help them if their cancer ever returns.