How would you approach a young patient with a prior ER+ HER2- breast CA now local recurrence that now has Her2 positive disease?

For Her-2 positive disease, I would definitely choose chemotherapy with anti Her-2 agent(s). With Her-2 positivity and a young age, the patient is at high risk for recurrence which can be significantly reduced by the addition of anti Her-2 agents to chemotherapy. Although this is a local recurrence, the immunohistochemical profile is different in the form of Her-2 positivity. Hence, I would almost treat like someone with a new primary. We have high quality data from studies such as the HERA, FinHer, NSABP-B31, NCCTG-N9831 and BCIRG-006 which suggest that chemotherapy agents along with anti Her-2 agents seem to improve disease free survival (DFS) and overall survival (OS) significantly. Studies where a non-chemotherapy approach has been used...