Impact of race/ethnicity on the MammaPrint genomic assay risk and prognosis in early breast cancer (EBC): A National Cancer Database (NCDB) analysis.

Abstract

564 Background: The 21-gene Oncotype DX Recurrence Score (RS) and 70-gene MammaPrint (MP) assays provide prognostic information for distant recurrence and are used to guide chemotherapy use in hormone receptor (HR)-positive, HER2-negative EBC. Previous reports have demonstrated that Black women with low genomic risk (RS 0-25) have a higher recurrence risk than White women in the TAILORx (PMID: 32986828) and RxPONDER trials (SABCS 2023, abstract GS1-01), and that Black race was associated with worse overall survival (OS) in multivariate models including RS in the NCDB registry (PMID: 33649322).The goal of this study was to evaluate the impact of race/ethnicity on MP risk distribution and prognostic information provided by the MP assay in the NCDB cohort. Methods: Women with HR-positive EBC with tumor size up to 5 centimeters (T1-T2), 0-3 involved lymph nodes (LNs, N0-N1), diagnosed between 2009-2018, and who had available information on MP testing and OS in the NCDB 2019 dataset were identified. Patients (pt) were stratified by MP result of high or low risk. T-tests and chi-square tests were used to compare pt characteristics, while log-rank tests assessed differences in OS between the high- and low-risk MP groups, as well as across different racial/ethnic categories. Results: 6096 eligible women were included of whom 41.0% (N=2502) were MP high-risk and 59.0% (N=3594) MP low-risk. Overall, 82.7% of pts were Non-Hispanic White (NHW), 8.7% Non-Hispanic Black (NHB), 4.7% Hispanic (H), and the remainder other/unknown (O). A higher proportion of H and NHB pts had high MP results, p<0.0001. The MP high-risk group had a greater proportion of pts </= 50 years (p=0.0013) and larger tumors (p<0.0001) and higher grade (p<0.0001), but not LN positive (p=0.7649). The 5-year OS rates (and 95% Confidence Intervals) for the MP high and low-risk groups were 92.6% (91.6% - 93.7%) and 96.6% (95.9% - 97.2%), respectively, p<0.0001. There were no differences in OS based on race/ethnicity in the low-risk group with 5-year OS rates of 98.4% (96.1%-100%), 95.9% (93.3% - 98.6%), 96.4% (95.7% - 97.1%), and 99.2% (97.7% - 100%) for H, NHB, NHW and O, respectively, p=0.34. Similarly, in MP high-risk, race/ethnicity did not impact prognosis with OS rates of 92.6% (88.2% - 97.1%), 90.8% (87.2% - 94.5%), 92.8% (91.7% - 94.1%), and 95.8% (91.2% - 100%) for H, NHB, NHW and O groups, respectively, p=0.45. There was no significant interaction between race and MP for OS when accounting for age, tumor grade, tumor size, and LN status, p=0.75. Conclusions: NHB and H women were more likely to have high-risk MP results compared with NHW women in this NCDB cohort, although race/ethnicity did not impact prognosis for 5-year OS in either MP risk group. Limitations of this analysis include absence of information on recurrence and short follow up, as about one-half of recurrences in HR-positive EBC occur after 5 years.