21-Gene Recurrence Score and Adjuvant Chemotherapy Decision for Breast Cancer Patients with Positive Lymph Nodes

The 21-gene recurrence score (RS) assay is prognostic and predictive for hormone receptor (HR)+/HER2-/node- breast cancer (BC) patients. However, its clinical value in node + patients hasn't been elucidated. HR+/HER2-/pN1 patients operated in Comprehensive Breast Health Center, Shanghai Ruijin Hospital from January 2014 to December 2018, with available RS results were retrospectively included. Clinico-pathological characteristics were compared. Adjuvant chemotherapy recommendations pre-/post- RS assay and actual usage were analyzed. A total of 303 patients were included, with 59, 178, 66 RS < 18, 18-30 and >= 31. Age (P < 0.001), comorbidity (P= 0.013), and RS category (P < 0.001) were independently associated with chemotherapy recommendation. Compared with low RS patients, those with intermediate (OR 6.58, 95%CI 2.37-18.31, P < 0.001) or high (OR 54.14, 95%CI 3.77-776.54, P= 0.003) RS were more likely to be recommended with chemotherapy. RS independently influence chemotherapy decision in postmenopausal population as well. Chemotherapy recommendation changed for 9.57% patients after RS assay. Patient adherence rate to chemotherapy recommendation was 94.72% (287/303). The 21-gene RS independently influenced chemotherapy recommendation in pN1 BC patients, which could provide additional information to guide chemotherapy decision with relatively good treatment adherence rate.