NRG-GI008: COLON ADJUVANT CHEMOTHERAPY BASED ON EVALUATION OF RESIDUAL DISEASE (CIRCULATE-US)

ctDNA-ve Cohort (Arms 1 + 2): Phase II: To compare time to ctDNA (+ve) status in ctDNA (-ve) cohort following resection of stage III colon cancer treated with immediate vs delayed (based on serial ctDNA surveillance) chemotherapy. Time to positive event is defined as time from randomization to the first ctDNA positive result for the immediate arm (Arm 1) and to the 2nd ctDNA positive result for the delayed arm (Arm 2) to allow for the potential effect of delayed adjuvant chemotherapy. Patients recurred without a positive ctDNA result will be considered to have ctDNA positive status at the time of recurrence for both study arms. Phase III: To compare time to DFS event (recurrence, second primary colorectal cancer or death) in ctDNA (-ve) cohort following resection of stage III colon cancer treated with immediate vs delayed (based on serial ctDNA surveillance) chemotherapy. ctDNA+ve Cohort (Arms 3 + 4): Phase II and III: To compare time to DFS event (recurrence, second primary colorectal cancer or death) in ctDNA (+ve) cohort following resection of colon cancer treated with 5-FU (or capecitabine) and oxaliplatin x 6 months or 5-FU, oxaliplatin and irinotecan x 6 months.