Dr Siddhartha Yadav: The Underutilization of BRCA Testing

At San Antonio Breast Cancer Symposium 2023, Siddhartha Yadav, MBBS, MD, of the Mayo Clinic, presented findings from a real world studying analyzing the utilization of BRCA testing and PARP inhibitors in HER2-negative metastatic breast cancer. Among the notable takeaways of his research, Siddhartha emphasized data revealing that the vast majority of patients go without germline BRCA testing.

Transcript

This transcript has been lightly edited.

Can you provide an overview of the use of BRCA testing and PARP inhibitors in HER2-negative metastatic breast cancer in the context of your study?

The NCCN [National Comprehensive Cancer Network] guidelines, and many national guidelines, recommend that we perform germline testing in patients with HER2-negative metastatic breast cancer so that we can offer PARP inhibitors for treatment. However, we have very limited data from real world settings. So, this was a study that we wanted to look into and see what happens in the real world. Even though all patients with HER2-negative metastatic breast cancer should undergo a germline BRCA testing, is that happening and what are rates? And so we utilized the US real-world data set from Flatiron [Health] to look into this. And Flatiron basically collects data from electronic medical records across different, several 100 clinical sites in the US. And what was surprising was that we found that less than 40%—so if you look at the entire data set—almost approximately 30% to 40% of patients with LG negative metastatic breast cancer underwent germline BRCA testing, which means that 60% to 70% of those patients who should have undergone testing did not undergo testing. So that's kind of the surprising finding of this study.

What are the clinical implications of your findings?

Yeah, so you know, if we think from an implications perspective, first and foremost, while it is surprising. There are other datasets that have also shown that there is clearly under testing of individuals for germline BRCA mutation in metastatic breast cancer. What this means is that there is a subset of patients who, because they have not been tested, would not be eligible for treatment with PARP inhibitors and are currently being undertreated. So, obviously, this is a huge challenge in the field because metastatic breast cancer is a highly lethal malignancy; there are limited treatment options. But if we don't even do testing to identify what treatment options patients would be eligible for, then obviously that does not help them either. So the implications are more so in terms of understanding where there are gaps in testing, and what can we do from a system perspective to improve these germline BRCA testing aids.