R.T.s surgical course is uneventful, and he is discharged after 5 days. Based on the final pathology report, his cancer is designated stage IIIB. The cancer had spread to the muscle layer of the colon wall with 9 lymph nodes being positive. Four weeks after surgery, R.T. is scheduled to begin 6 months of adjuvant chemotherapy.10. Current chemotherapy protocols include varying doses of fluorouracil and leucovorin alone or in combination with oxaliplatin or irinotecan. The purpose of leucovorin is to: