This study will evaluate how a laboratory test, Signatera, is used to manage care of patients with stage II or III colorectal cancer. Signatera is a laboratory test that uses DNA from a tissue sample to measure circulating tumor (ct)DNA in the blood. The patients enrolled in this study will have Signatera™ ctDNA testing performed as part of their routine care. This is an observational study, which means it will not change the regular medical care patients will receive from their doctor. The study will look at how Signatera™ test results affect patient care decisions and outcomes.