How would you manage adjuvant treatment of a premenopausal woman with HER2 positive, ER/PR negative multifocal micro-invasive node-negative breast cancer?  

I would not typically recommend any adjuvant chemotherapy + HER2 directed therapy for a T1mi N0 breast cancer. For T1a, the risk of distant recurrence also is likely low based on observational series, so observation is also reasonable. However, as per NCCN guidelines, it is also appropriate to consi...