Case 2: ER+ Breast Cancer

Hope Rugo, MD, FASCO: I think what we’ll do now is move on and talk about an interesting case of hormone receptor–positive breast cancer, which is the most common subset of breast cancer that we all see in the early- and late-stage settings. Dr Adam Brufsky is going to talk about a case from his practice and then review some of the data that we use to try and make decisions for patients who have hormone receptor–positive breast cancer. And then we’ll talk about how this impacts our decision making. Thanks. Adam?

Adam Brufsky, MD, PhD: Thanks a lot. This is the case of estrogen receptor–positive breast cancer. This is a 63-year-old woman who was diagnosed with a 3.5-centimeter right-side infiltrating ductal carcinoma. She actually—as some of our patients do—refused surgery. She refused endocrine therapy. She really didn’t want to do anything. She went off, and we didn’t see her again for a while. She then comes back a little more than a year later, and her cancer has progressed. It’s now 6 centimeters. We do labs, and her liver function tests are normal.

We happened to scan her because she now has T3 disease. In our practice, our cutoff for doing scans on people is generally T3—really what we consider stage 3 and above. So we do it, and the CAT scan shows 2 liver nodules. The largest is 2 centimeters. We biopsy it, and it’s a grade 2. It’s not an infiltrating ductal carcinoma. They usually call it poorly differentiated carcinoma. Actually, it really wasn’t poor. It was fairly strong estrogen receptor–positive, about 80%; progesterone receptor–positive, about 50%; and HER2 negative.

At this point, she’s obviously staged as metastatic disease. Despite all this, her performance status was really good. It was 0. The question now is what to do with her. We have data from the NCCN [National Comprehensive Cancer Network] here. The preferred first-line regimen, which I think we’re all very familiar with, is an aromatase inhibitor [AI] with a CDK4/6 inhibitor. There’s really no preference in regard to which CDK4/6 inhibitor. I think there are occasions, and I think some of us may use fulvestrant first. I basically say to use fulvestrant for the people who are already on an aromatase inhibitor. But I’ll use that with a CDK4/6 inhibitor.

Other drugs are clearly available, including other options without a CDK4/6. But as I’m going to show you in a minute, I think there is emerging survival benefit, definitely in the second-line setting, with these agents. Then, obviously, the second line is what they didn’t get before. Someone should probably get fulvestrant and a CDK4/6 inhibitor if they have had an AI and have not had a CDK4/6. We can talk about PI3 kinase–mutated tumors. Those are people who are already progressed through a CDK4/6 inhibitor—probably fulvestrant and a CDK4/6.

There is everolimus, etc, as well as other antihormonal agents.

Transcript edited for clarity.