There are often multiple options presented to patients after completing surgery for colon cancer. This study is designed to evaluate what specific kinds of chemotherapy to recommend to patients based on the presence or absences of circulating tumor DNA (ctDNA). If you are assigned to the group that is to be tested for ctDNA every 3 months, you will have regular check-ups at 3 and 6 months after you join the study and then every 6 months after you join the study without further treatment for your colon cancer. If you develop a positive ctDNA test during this testing, you will be asked to join the ctDNA positive group and to agree to receive chemotherapy for 6 months with the usual chemotherapy drug combinations, FOLFOX or CAPOX, or with another chemotherapy drug combination of 5-fluorouracil (5-FU), leucovorin, oxaliplatin, and irinotecan called mFOLFIRINOX. During screening, patients will sign consent, have a physical exam, vitals performed, labs drawn, an imaging scan, and central ctDNA testing. While on study treatment, at visits, patients will have physical exams, labs drawn, imaging scans, and adverse event assessments.