What adjuvant therapy would you give to a patient with resected pT4bN2M0 MSI-H colon cancer and post-op markedly elevated CEA but no metastatic disease seen on imaging?

This patient has a high-risk stage III MSI-H colon cancer with persistently elevated CEA without radiographic evidence of disease (given the persistent elevated CEA after surgery, I would get a PET-CT to rule out occult metastatic lesion).

The standard answer should be oxaliplatin-based systemic adj...