Are there any adverse risk factors in stage I colon cancer that would warrant ctDNA testing?   

I would not check ctDNA in this setting. If there is an adverse feature of the tumor and the patient is a candidate for further treatment, I would do close surveillance imaging and CEA at the most. A recent publication of a larger cohort study of stage II to IV resected colorectal cancer suggests th...

This is a great question and we have limited data.  The best evidence would be from the Circulate-Japan study which included 228 pathological stage I colon cancer patients. The positive rate in this population is extremely low in the MRD window (only 2 positive, means positive rate <1%) so ...