Sara Tolaney, MD, MPH: Let’s dive into our first case. This is a 56-year-old postmenopausal woman who presented with a new left breast mass. At the time, there was no evidence of enlarged axillary lymph nodes. There was a biopsy done of the breast abnormality, and that came back as an invasive ductal carcinoma that was strongly ER [estrogen receptor] positive at 100%. PR [progesterone receptor] was also strongly positive. HER2 [human epidermal growth factor receptor 2] IHC [immunohistochemistry] was 0 and not also amplified for HER2 by FISH [fluorescence in situ hybridization]. Ki-67 was done and was high, at 46%.

It was decided that she would undergo up-front surgery. She had a mastectomy that revealed a 2.5-cm grade 2 invasive ductile carcinoma with 1 of 3 axillary nodes; margins were negative. The decision was then made about what her adjuvant systemic therapy should be. She ended up getting started on letrozole with abemaciclib.

Let’s take a step back and think about this case. If you saw this patient, what would you think in terms of understanding her risk? Do you think additional tests should have been sent? For example, outside what we know with having the high Ki-67, would you send a genomic assay—like a 21-gene recurrence score—to help you decide the utilization of chemotherapy in this setting?

Massimo Cristofanilli, MD: Absolutely. This is the type of case that gets discussed at the multidisciplinary clinic where the surgeon gets the patient from a postbiopsy mammogram. Clearly [the patient] is a candidate for surgery. Considering some of the pathological factors, maybe she’ll need chemotherapy. We discuss the use of molecular testing to stratify patients. If you want to send an Oncotype DX to see if this patient has high-risk, high-recurrence score, that will be starting a conversation: does she need chemotherapy? Should we do chemotherapy up front so we can evaluate the response?

We know that ER+ patients don’t achieve pathologic CR [complete response] frequently. But in cases like this, you can test the sensitivity to the neoadjuvant therapy if the patient is favorable to that. Of course, there are no surgical issues in this case. She was electing already for mastectomy. Didn’t have a stand-down stage. In clinic, there were no lymph nodes. If there were lymph nodes, there would be another argument in favor of that. But an Oncotype DX test would be absolutely appropriate. As we know from the guidelines and data, most of the value for predicting the benefit of chemotherapy is in postmenopausal patients.

Sara Tolaney, MD, MPH: I very much agree. I would also have sent a recurrent score. One would [think] that with that high Ki-67, maybe she would also have had a high recurrent score. If that were the case postsurgery, she would have started with adjuvant systemic chemotherapy.

Transcript edited for clarity.