How would you approach adjuvant therapy for a young post-menopausal woman with a grade 3 pT1a (5mm) node negative ER+/HER2- invasive ductal carcinoma?

There is no data from the prospective trials to support genomic testing in T1a tumors. TAILORx did not enroll T1a tumors. A G3 tumor under 1cm is clinically low risk so Mammaprint would not have clinical utility either. Since NCCN doesn't recommend chemotherapy in this scenario, I would not test.

I will recommend adjuvant Hormone Therapy.