What adjuvant therapy would you recommend for a woman in her 90s with ER-positive, HER2-positive breast cancer who received neoadjuvant trastuzumab, pertuzumab, and anastrozole, but did not achieve a pathologic complete response?

I agree with Dr. @Dr. First Last that the available information is extremely limited. Was the decision to avoid neoadjuvant chemotherapy based solely on age, or were other comorbidities or functional status considerations involved? If she were not a candidate for standard chemotherapy, it is likely that she would not be a candidate for T-DM1 either.

Furthermore, because she did not receive the standard neoadjuvant regimen with chemotherapy, pCR cannot be used as the endpoint to guide a risk-adap...

The clinical information provided is extremely limited (number of neoadjuvant cycles given, node-negative versus node-positive, RCB, toxicity, comorbidities) to provide a definitive recommendation. Therefore, to continue on current therapy or transition her to ado-trastuzumab, T-DM1, and anastrozole are obvious options. Of note, she did not meet the inclusion criteria for the KATHERINE trial.