Prognostic value of the 21-gene recurrence score in ER-positive, HER2-negative, node-positive breast cancer was similar in node-negative diseases: a single-center study of 800 patients.

Multi-gene assays have emerged as crucial tools for risk stratification in early-stage breast cancer. This study aimed to evaluate the prognostic significance of the 21-gene recurrence score (RS) in Chinese patients with pN0-1, estrogen receptor-positive (ER), human epidermal growth factor receptor 2-negative (HER2) breast cancer. Among 800 patients recruited between 2009 and 2016, the median RS was 24 (0-69), with 27.4%, 46.8%, and 25.9% patients classified into low-, intermediate-, and high-risk groups. Cox regression analysis demonstrated that the high-risk category was associated with significantly higher odds of invasive disease-free survival (IDFS) and distant disease-free survival (DDFS) events compared with the low-risk category (IDFS: HR = 2.450, 95% CI 1.017-5.902, P = 0.046; DDFS: HR = 2.829, 95% CI 1.013-7.901, P = 0.047). No significant association between RS category and overall survival (OS) was found (intermediate vs. low: HR= 1.244, 95% CI 0.292-5.297, P = 0.768; high vs. low: HR = 2.933, 95% CI 0.759-11.327, P = 0.119). RS, as a continuous variable, was a highly significant predictor for IDFS (HR= 1.028, 95% CI 1.010-1.047, P = 0.002), DDFS (HR= 1.030, 95% CI 1.010-1.051, P = 0.003), and OS (HR= 1.034, 95% CI 1.007-1.063, P = 0.014). Our findings suggested that RS may predict IDFS in Chinese patients with ER/HER2 breast cancer with N0 or N1 disease.