Research Studies

- Patients must have histologically/pathologically confirmed Stage IIIA or Stage IIIB colon adenocarcinoma (T1-3, N1/N1c) with R0 resection accordingly to AJCC 8th edition criteria. NOTE: Patients with pathologic stages II or IIIC colon adenocarcinoma with R0 resection who have a commercially obtained Signatera ctDNA+ve assay result post-operatively meeting all timelines and eligibility requirements otherwise, are eligible for enrollment and inclusion in Cohort B. - No radiographic evidence of overt metastatic disease within 28 days prior to study entry (CT with IV contrast or MRI imaging is acceptable and must include chest, abdomen, and pelvis). - The distal extent of the tumor must be ≥ 12 cm from the anal verge on colonoscopy or above the peritoneal reflection as documented during surgery or on pathology specimen (i.e., excluding rectal adenocarcinomas warranting treatment with chemoradiation). - The patient must have had an en bloc complete gross resection of tumor (curative resection). Patients who have had a two-stage surgical procedure, to first provide a decompressive colostomy and then in a later procedure to have the definitive surgical resection, are eligible. - The resected tumor specimen and a blood specimen from patients with Stage IIIA or Stage IIIB colon cancer must have central testing for ctDNA using the Signatera assay by Natera. - Tumor must be documented as microsatellite stable or have intact mismatch repair proteins through CLIA-approved laboratory testing. Patients whose tumors are MSI-H or dMMR are excluded. - The interval between surgery (post-operative Day 7) and study entry must be no more than 60 days. - NOT PERMITTED: Any prior systemic chemotherapy, targeted therapy, or immunotherapy; or radiation therapy administered as treatment for colorectal cancer (e.g., primary colon adenocarcinomas for which treatment with neoadjuvant chemotherapy and/or radiation is warranted are not permitted).