How would you treat a postmenopausal woman with recurrent, localized ER+,HER2- breast cancer to the contralateral breast while on AI?

Assuming this a new primary, you would treat it like another primary breast cancer with breast surgery +/- radiation. If clinically appropriate you would send genomic testing (i.e., Oncotype or Mammoprint) to make decisions about adjuvant chemotherapy. The contralateral breast cancer (CBC) recurrenc...

I would not consider this recurrent but a new primary since is contralateral. For that reason I would use tamoxifen r/t AI although the data really don't exist. That said, I would probably be more proactive about considering chemotherapy since this cancer clearly has clinical evidence of at least re...

I think the suggestion of doing NGS is very appropriate here. This tumor developed on an AI and therefore despite the fact ESR1 mutations are rare in primary tumors not exposed to AI , this would not necessarily be the case with a patient continuously on an AI. Activating ESR1 mutations are associat...

In such situations, I agree with metastasis work up, obtaining next gen sequencing/oncotype score in addition to assessing tumor grade and Ki-67. Consider neoadjuvant fulvestrant+/-cdk4-6 inhibitor, monitoring rx response, reassessing Ki-67, grade, and PEPI score after maximal response. This will al...