Examining Validity of Breast Cancer Biomarker in Diverse Women

A population-based study by University of Illinois Cancer Center members and others raises the possibility that the Oncotype 21-gene breast recurrence score (RS), the most commonly ordered multigene breast cancer biomarker in the United States, might underestimate the benefit of chemotherapy for non-Hispanic Black women, which could perpetuate racial disparities in breast cancer survival of estrogen receptor (ER)-positive, HER2-negative tumors by misguiding treatment recommendations.

The study, “Reduction in Breast Cancer Death With Adjuvant Chemotherapy Among US Women According to Race, Ethnicity, and the 21-Gene Recurrence Score,” was published in the official Journal of the National Comprehensive Cancer Network (JNCCN) on January 8.

The predictive biomarker 21-gene RS was developed to inform which patients are or aren’t likely to benefit from adjuvant chemotherapy. The NCCN Clinical Practice Guidelines in Oncology for Breast Cancer base its recommendation on the RS for ER-positive tumors with no armpit lymph node metastases.

Findings on Breast Cancer Biomarker

“This population-based study clinically validated the RS as a predictive biomarker for NHB (non-Hispanic Black), Hispanic, and NHW (non-Hispanic white) women with ER-positive, axillary node–negative breast cancer, but it also raises the possibility that the RS may underestimate the benefit of chemotherapy for NHB women. If confirmed, the RS cutoff for recommending adjuvant chemotherapy for young NHB women with ER-positive, axillary node–negative breast cancer may need to be lower than for other women. This study also underscores the need to account for the racial and ethnic diversity of the target population in the development and validation of cancer biomarkers,” the authors concluded.

Cancer Center authors are Kent Hoskins, MD, Oncology Service Line Medical Director at UI Health and Cancer Center Director for Translational Oncology; VK Gadi, MD, PhD, Cancer Center Deputy Director; Oana C. Danciu, MD, Cancer Center Associate Director for Clinical Research; and Garth H. Rauscher, PhD. Other authors are Hsiao-Ching Huang, MPH, UIC College of Pharmacy; Jennifer Weiss, MD, and Yael Simons, MD, both past fellows in the UIC Hematology and Oncology Fellowship Program; and Gregory S. Calip, PharmD, MPH, PhD, University of Southern California, Los Angeles.

Read more about the study in UIC Today.

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