For patients with resected colon cancer, to what extent would you adapt adjuvant chemotherapy if ctDNA results don't correspond with your initial treatment recommendation?

Data in this field is evolving quickly. We will have more answers in the upcoming months as BESPOKE, SU2C MGH, more follow-up on PEGASUS presented at ESMO a few weeks ago, as well as CIRCULATE-JAPAN and CIRCULATE-US accrue and read out.

Till that, the strongest evidence would be from what happened to...

As several studies in this area are still ongoing, the recommendation ultimately relies on shared decision-making with the patient. Based on the current evidence, if the patient declines or is ineligible for one of the adjuvant studies and ctDNA is positive, I recommend extending therapy to six mont...

This is not (yet) an easy-to-answer question. I'll try to address this from a practical standpoint. CtDNA has been shown to be prognostic in multiple prospective and retrospective studies. Is this sufficient to routinely use it in the care of stage II/III colon cancer patients? I have to start by sa...

I use ctDNA most in stage II cancer, where there is equipoise whether or not to give chemotherapy at all. For a ctDNA+ patient, I recommend an oxaliplatin doublet. In stage III, if a patient is ctDNA-, I will use this to stop chemotherapy early for a patient who is not tolerating treatment well. For...

Addressing each of the posed scenarios individually:

• If you had recommended 6 months 5-FU and the initial ctDNA is positive, do you transition to a doublet?
  There is no data yet to use ctDNA to change your treatment recommendations and would still strongly urge clinical trials. Caution must also be ...

This is a complex and evolving space and currently, we do not have sufficient data to provide high-level evidence of treatment decisions with ctDNA. That being said, in addition to what Dr. @Dr. First Last and Dr. @Dr. First Last have noted, a few practical considerations to take into account:

• If yo...