How would you manage adjuvant treatment of a patient with ER+/PR+/HER2+ breast cancer and a small amount of residual disease (e.g. T1mi) following neoadjuvant TCHP?

The benefit for TDM1 was seen in the subset analysis of KATHERINE patients with residual tumors under 1cm (including T1mic) HR .66 and about a 5% absolute risk reduction. So I agree with @Dr. First Last that switching to TDM1 should be discussed with the patient.

This is a very tough question. The KATHERINE trial allowed patients with any residual disease following neo-adjuvant chemotherapy. Based on analysis by Symmans et al., patients with HER2 positive breast cancer who had residual cancer burden (RCB) class I (minimal residual disease) had a 10-year even...

I agree with the responses above. In the KATHERINE trial, the benefit was seen with T-DM1 among ypT1a, ypT1b, and ypT1mic patients who consisted of at least 40-44% of the cohort (for the intervention and the control groups, suggesting the benefit across all groups). Given this data, one will be incl...

Yes, for only microscopic residual disease, node-negative. We need more data in the future.