Case 1: Role of Ki67 Testing in HR+ Early Breast Cancer
Sunil Badve, MD, FRCPath, and Heather McArthur, MD, evaluate best practices around Ki67 assessment when approaching treatment for HR+ early breast cancer.
Joyce O’ Shaughnessy, MD: Sunil, is this now standard? What’s your pathology? Let’s say people hadn’t been doing Ki67. Do they now need to do it on all ER [estrogen receptor]–positive, HER2-negatives? What would you recommend to pathologists?
Sunil Badve, MD, FRCPath: The first thing is that no decision about patient treatment should be made in isolation. It’s important to discuss this with the multidisciplinary team and make sure that everybody is on board at your institution. With that being said, we have started doing Ki67 on every patient at the time of diagnosis, partly because it becomes easier in terms of workflow issues, and we have plenty of data saying high proliferation is a bad marker and a good indicator for chemotherapy, while with lower proliferations, the patients may not do as well with chemotherapy. We have had that great information for a long time, but people didn’t quite believe it. Now that we have the Ki67 information, it’s clearly a very valuable piece in patient management and I’d recommend everybody to start doing it if they haven’t been.
Joyce O’ Shaughnessy, MD: Thanks. Heather, how about you guys at UT Southwestern Medical Center? Do you guys get it done routinely or just on certain patients?
Heather McArthur, MD: We get it done routinely on all our patients. At my last institution, we did as well, but there are a number of institutions, including Dana-Farber Cancer Institute, that aren’t routinely testing for Ki67. There are still some disparate practices in this regard. As Massimo said earlier, we’re all still learning about best practices. Some of the pushback has been the challenges and inconsistencies in reporting and interobserver variability in several studies. A lot of groups have pushed back on the idea of using Ki67 and have leaned more toward the ASCO [American Society of Clinical Oncology] and NCCN [National Comprehensive Cancer Network] guidelines that don’t incorporate Ki67.
Joyce O’ Shaughnessy, MD: Thanks. What do you think? Who are you starting to think about this in? Do you want to see a high Ki67 like the FDA [Food and Drug Administration] label said or is 4 more nodes enough? Who are you thinking about for this?
Heather McArthur, MD: I wasn’t very surprised by the benefit of CDK4/6 inhibitor in the curative-intent setting given what we learned in the metastatic setting. I was a little surprised that PALLAS trial, which was initially reported at the same time, didn’t demonstrate a benefit. But what’s really interesting about the monarchE trial data is the magnitude of the benefit with only 27 months of follow-up. That’s such early follow-up for ER-positive disease. It was a game-changer to see a delta of 5.4% as early as 3 years and that hazard ratio as you pointed out, with about 30% reduction in invasive disease-free survival and consistent benefits in the forest plot that you showed across all subgroups, particularly without early follow-up.
I was interested to learn that in cohort 1, approximately 55% of patients with 4 or more lymph nodes positive had a low Ki67. That was an interesting observation, and I was impressed by those exploratory analyses by Ki67 that you presented. Ki67 is performed routinely at my institution, so I have that information available to me. However, if I saw a patient with a Ki67 of 19% with 8 lymph nodes, that’s someone I’d still consider for adjuvant abemaciclib in accordance with the ASCO and NCCN guidelines. I’m thinking about my high-risk patients either as defined by the monarchE eligibility criteria or the number of lymph nodes involved. I’m using whichever definition is most convenient for the patient sitting in front of me.
Joyce O’ Shaughnessy, MD: That would be, “You’re high risk. We need to give you the very best possible.”
Transcript Edited for Clarity
Breast Cancer Leans into the Decade of Antibody-Drug Conjugates, Experts Discuss
September 25th 2020In season 1, episode 3 of Targeted Talks, the importance of precision medicine in breast cancer, and how that vitally differs in community oncology compared with academic settings, is the topic of discussion.
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