25 Real-world BRCA1/2 Testing Patterns in HER2–Negative Early- Stage Breast Cancer (eBC) Patients

Background

Clinical trials have demonstrated improved disease-free survival and overall survival in HER2-negative early-stage breast cancer patients with germline BRCA1/2 mutations who received adjuvant PARP inhibitors. It remains critical to assess BRCA1/2 testing patterns in clinical care to ensure that patients have access to all treatment options. There is limited real-world evidence on patient demographics and clinical characteristics differences in BRCA1/2 testing rates among HER2 negative eBC patients.

Materials and Methods

In this retrospective cohort study, HER2-negative eBC patients were identified using ICD-10 codes c50 series from May 1, 2020, through May 31, 2022, in the IntegraConnect (IC) database. The IC database is a comprehensive database that links patient electronic medical records with practice management and claims data. Descriptive analyses for categorical data were reported as counts and percentages, and continuous data were summarized as medians (IQR) comparisons across groups were conducted with t-tests and ANOVA. Chi-square and Fisher’s exact tests were used to compare proportions across categorical variables.

Results

The analytic cohort included 395 HER2-negative eBC patients of which 68% had documented BRCA testing. Tested patients were younger than untested patients (median age: 55 y vs 63 y) and premenopausal status was linked to higher rates of testing (89% vs 61% in postmenopausal women). BRCA1/2 testing was also higher among triple-negative breast cancer patients (TNBC) (74%) compared to hormone receptor-positive (HR+) patients (61%). In clinical settings, it was more common to test for BRCA1/2 before adjuvant therapy in both HR+ (86%) & TNBC (68%). A higher proportion of HR+ patients received germline testing for BRCA (72%) compared to TNBC patients (45%).

Conclusions

We found a testing rate for BRCA1/2 of 68% in US HER2-negative eBC patients receiving routine care. We noted unadjusted differences across patient demographics and clinical attributes between receipt of BRCA1/2 testing vs no receipt of testing. Efforts should focus on increasing the adoption of BRCA1/2 testing for all eligible patients to enhance adherence to guideline-recommended precision medicine options and subsequent outcomes.

AFFILIATIONS:

Gieira S. Jones,¹ Liam C. Lee,¹ Erin Alwon,² Brandon Wang,² Poras Dave,² Sandy English,² Prateesh Varughese,² Simon Blanc,² Arthur Sillah¹

¹Merck & Co, Inc, Rahway, NJ.

²Integra Connect, West Palm Beach, FL.