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 adjuvant chemotherapy based on the data (Cohen et al., PMID 33356421.)

We do not know the details of this patient (age, performance status, comorbidities, etc) so it is very hard to know if the patient i...