Improving personalized cancer treatments and finding the best strategies to treat each patient relies on using new diagnostic technologies. Currently, for colorectal cancer, the methods used to decide who gets additional post-surgery treatment are suboptimal. Some patients get too much treatment, while others do not get enough. There is a new way to explore if there is any cancer left in a patient's body using circulating tumor DNA (ctDNA) detected in blood samples. This can help decide who needs more treatment after surgery. Even though many tests have been developed, it has yet to be determined which test performs best at relevant time points. The GUIDE.MRD consortium is a group of experts, including scientists, technology, and pharmaceutical companies. The consortium is working on creating a reliable standard for the ctDNA tests, validating their clinical utility, and collecting data to help decide on the best treatment for each patient. GUIDE.MRD-01-CRC is a part of the GUIDE.MRD project.