Impact of a 21-Gene Recurrence Score Test on the Choice of Adjuvant Chemotherapy for Hormone Receptor-positive Early-stage Breast Cancer: A Prospective Study.

BACKGROUND: Studies have recommended a 21-gene recurrence score (RS) to optimize adjuvant treatment for patients with early-stage breast cancer (EBC) with hormone receptor-positive (HR(+)) and human epidermal growth factor receptor-2 negative (HER2(-)) tumors. This study aimed to prospectively evaluate the impact of this RS in Chinese patients with breast cancer.

PATIENTS AND METHODS: We prospectively collected 227 patients with EBC with estrogen receptor-positive (ER(+)) and HER2(-) tumors. We used one-way analysis of variance to compare the distribution of different risk groups based on a 21-gene RS assay. A Kruskal-Wallis test and either a chi-square or Fisher's exact test were used as appropriate to compare continuous and categorical variables, respectively.

RESULTS: Of the 227 eligible women enrolled, 61.2%, 30%, and 8.8% of patients were in the low (≤17), intermediate (18-30) and high (≥31) RS groups, respectively. Of the patients with a low RS, 74.8% were overestimated into the intermediate-risk group by St. Gallen risk. The overall impact of the 21-gene RS was reduced use of chemotherapy (78/227, 34.4%). In addition, Ki67 expression was positively associated with the 21-gene RS (R=0.68).

CONCLUSION: Among patients with ER(+)/HER2(-) EBC, the 21-gene RS was an effective method for making a chemotherapy decision. Ki67 was associated with 21-gene RS.