TUESDAY, Feb. 6, 2024 (HealthDay News) — The 21-gene breast recurrence score (RS) is valid for predicting chemotherapy benefit for non-Hispanic Black (NHB), Hispanic, and non-Hispanic White (NHW) women with estrogen receptor (ER)-positive, axillary node-negative breast cancer, but the test may underestimate chemotherapy benefit for young NHB women, according to a study published online Jan. 8 in the Journal of the National Comprehensive Cancer Network.

Hsiao-Ching Huang, M.P.H., Ph.D., from the University of Illinois College of Pharmacy in Chicago, and colleagues determined the clinical validity of the RS for predicting chemotherapy benefit as recommended in the current National Comprehensive Cancer Network Guidelines for Breast Cancer. The propensity score-weighted hazard ratios were estimated for breast cancer death with chemotherapy for women with ER-positive, axillary node-negative, invasive breast cancer. Data were included for Asian/Pacific Islander (API), NHB, Hispanic, and NHW women (8.2, 7.8, 9.1, and 74.9 percent, respectively).

The researchers found that for NHB, Hispanic, and NHW women with an RS of 26 to 100, breast cancer death was reduced with chemotherapy (hazard ratios, 0.48, 0.48, and 0.80, respectively). A nonsignificant reduction was seen for API women. No reduction in death was seen for women with an RS of 11 to 25, regardless of racial/ethnic group. The reduction in breast cancer death with chemotherapy varied according to race among women aged 50 years or younger (hazard ratios, 0.37 and 0.56 for NHB and NHW, respectively). Data from an exploratory subgroup analysis suggested young NHB women may benefit from chemotherapy at a lower RS cutoff than 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 write.

Several authors disclosed ties to the biopharmaceutical industry.

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