Impact of 21 Gene Recurrence Score on Chemotherapy Decision in Invasive Ductal Carcinoma of Breast with Nodal Micrometastases
Purpose The purpose of this study was to investigate the effect of 21 gene recurrence score (RS) on predicting prognosis and chemotherapy decision in node micrometastases (N1mi) breast invasive ductal carcinoma (IDC) Methods Patients with stage T1 2N1mi and estrogen receptor positive IDC diagnosed between 2004 and 2015 were included. The associations of 21 gene RS with breast cancer specific survival (BCSS) chemotherapy decision, and benefit of chemotherapy were analyzed. Results We identified 4,758 patients including 1,403 patients (29.5% treated with adjuvant chemotherapy. In the traditional RS cutoffs, 2,831 (59.5% 1,634 (34.3% and 293 (6.2% patients were in the low intermediate and high risk RS groups, respectively. In 3,853 patients with human epidermal growth factor receptor 2 (HER2) status available, most patients were HER2 negative disease (98.3% A higher RS was independently related to chemotherapy receipt, and 14.0% 47.7% and 77.8% of patients in the low intermediate and high risk RS groups received chemotherapy, respectively. The multivariate analysis indicated that a higher RS was related to worse BCSS (p 0.001) The 5 year BCSS rates were 99.3% 97.4% and 91.9% in patients with low intermediate and high risk RS groups, respectively (p 0.001) However, chemotherapy receipt did not correlate with better BCSS in low intermediate or high risk RS groups. There were similar trends using Trial Assigning Individualized Options for Treatment RS cutoffs. Conclusion The 21 gene RS does predict outcome and impact on chemotherapy decision of N1mi breast IDC. Large cohort and long term outcomes studies are needed to identify the effects of chemotherapy in N1mi patients by different 21 gene RS groups.
Cancer research and treatment official journal of Korean Cancer Association