The 21-gene recurrence score (RS) predicts the prognosis of patients with estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative early-stage breast cancer and the effectiveness of adding adjuvant chemotherapy on the basis of endocrine therapy to avoid excessive chemotherapy. The present study aimed to analyze clinicopathological characteristics and chemotherapeutic efficacy-related target genes with the 21-gene RS in hormone receptor-positive early-stage breast cancer in China. The prognostic value of chemotherapeutic efficacy-related target genes was also examined. In addition, this study investigated the postoperative adjuvant therapeutic decision-oriented role of 21-gene RS in hormone receptor-positive and lymph node-negative early-stage breast cancer. In the present retrospective study, 110 ER+/HER2- early-stage breast cancer patients were tested with the 21-gene RS. The analyses of clinicopathological characteristics and chemotherapeutic efficacy-related target genes with the 21-gene RS were performed using the χ2 test, the Wilcoxon rank-sum test and binary logistic regression. Kaplan-Meier survival plots were drawn in www.kmplot.com. Furthermore, the McNemar χ2 test was used to compare the changes of treatment decisions before and after the 21-gene test. The median RS of 110 patients was 16 (range, 2-47), and patients were categorized as low (59.1%), intermediate (34.5%) or high risk (6.4%). The results revealed that higher body mass index, invasive ductal carcinoma type, higher histological grade, luminal B molecular type and higher thymidylate synthetase (TYMS) and DNA topoisomerase IIα (TOP2A) gene expression levels were more likely to have a higher RS. Kaplan-Meier plots suggested that expression of TYMS, tubulin β3 class III (TUBB3) and TOP2A genes was significantly associated with relapse-free survival for ER+ breast cancer. Additionally, prior to 21-gene RS testing, 61 patients (55%) were recommended adjuvant chemotherapy and endocrine therapy; however, following 21-gene test, 32 patients (29%) were treated with only adjuvant endocrine therapy. TYMS, TUBB3 and TOP2A gene expression may have prognostic value for ER+ breast cancer. In addition, 21-gene RS testing may aid to avoid excessive postoperative adjuvant chemotherapy.
Keywords: 21-gene recurrence score; breast cancer; clinicopathological characteristics; gene expression; prognosis.