Distribution, Chemotherapy Use, and Outcome of the 21-Gene Recurrence Score Between Chinese and White breast Cancer in the United States.

Purpose: To compare the distribution, chemotherapy-decision making, and prognosis of the 21-gene recurrence score (RS) between Chinese breast cancer (BC) in the United States and White American (WA) BC.

Methods: We identified early-stage and estrogen receptor-positive BC patients diagnosed between 2004 and 2015. Multivariate logistic regression, Kaplan-Meier analysis, and multivariate Cox proportional hazards models were used for statistical analyses.

Results: A total of 67,486 patients were identified, including 66,215 (98.1%) WA patients and 1271 (1.9%) Chinese patients. Regarding the RS, 38,894 (57.6%) had low RS, 23,882 (35.4%) had intermediate RS, and 4710 (7.0%) had high RS. A similar distribution of RS was found between WA and Chinese BC (P = .280). The race was not the predictor associated with high RS. Similar trends of chemotherapy use were found in Chinese and WA BC. In WA BC, there were 4.1%, 31.5%, and 72.2% of patients receiving chemotherapy in low, intermediate, and high RS cohorts, respectively (P < .001). The proportion of chemotherapy use was 6.8%, 30.9%, and 74.0% in Chinese BC with low, intermediate, and high RS cohorts, respectively (P < 0.001). The multivariate prognostic analyses indicated that a higher RS was independently associated with an inferior breast cancer-specific survival. Similar trends were found among those with Chinese and WA BC.

Conclusion: Our results demonstrate similar distribution, chemotherapy use, and outcome of the 21-gene RS between Chinese and WA BC in the United States.