Would you send Oncotype for pre-menopausal women with HR+, HER2(-) breast cancer with a small tumor (pT1b) and micrometastatic LN involvement or recommend adjuvant chemotherapy without sending Oncotype?

That is a very good question, especially considering that the RxPONDER trial showed benefit from chemotherapy in pre-menopausal women with 1-3 lymph nodes involved by breast cancer. However, this trial excluded patients who had micro-metastatic disease as the only nodal involvement, so we can't apply these results to such patients. We, therefore, do not know if the Oncotype Dx recurrence score is predictive of chemotherapy benefit in this patient population. We also know from prior trials, that ...

The NCCN recommends that for premenopausal patients with HR-positive, HER2-negative breast cancer and pN1mi (micrometastatic lymph node involvement), a gene expression assay should be considered to assess prognosis when the patient is a candidate for chemotherapy. Importantly, the NCCN algorithm groups pN1mi together with pN1 (1–3 positive nodes) in the same treatment pathway for premenopausal patients with pN+ tumors, meaning Oncotype DX can be sent in this setting.

If the recurrence score ≥26...