The population characteristic analysis in RecurIndex for clinical decision-making on adjuvant therapy for early breast cancer: Results of a real-world study.

Abstract

e12514 Background: 28-gene signature (RecurIndex) is the first multi-gene panel for recurrence risk prediction after surgery developed from the Asian breast cancer population. In this study, we aimed to report the clinical and genomic characteristics of Chinese early-stage breast cancer patients whose primary lesions have been evaluated by 28-gene signature testing. Methods: In this study, 363 patients were assessed by 28-gene signatures between November 2019 and August 2021. Of these, 330 (90.9%) had stage I-II, hormone receptor-positive, HER2-negative breast cancer, 16 (4.4%) had triple-negative breast cancer (TNBC), and 17 (4.7%) had HER2-enriched breast cancer. The genomic risks of local and distant recurrence were determined by 28-gene signature respectively; the clinical risk was evaluated by the modified Adjuvant! Online. The molecular subtyping of the 28-gene signature was also compared with immunohistochemistry (IHC) status. In the future analysis, we will report the clinical decisions and outcomes of these patients. Results: The 28-gene signature classified 86.8% (n = 315/363) of patients as genomic Low Risk (LR) and 13.2% (n = 48/363) as genomic High Risk (HR) for local recurrence; 83.7% (n = 304/363) and 16.3% (n = 59/363) for distant recurrence. Among clinical HR patient, a total of 72 patients (64.9%) were deemed to be genomic LR of distant recurrence, and a total of 88 patients (79.3%) were deemed to be genomic LR of local recurrence. The concordance of luminal type identified by IHC or 28-gene based molecular subtyping was 99.1% (n = 327/330); TNBC type was 25% (n = 4/16), and HER2 enriched was 70.6% (n = 12/17). Conclusions: This study showed that in clinical HR patients, 64.9% 28-gene LR patients who could waive their adjuvant chemotherapy and 79.3% who could have the adjuvant radiotherapy adjusted. Additionally, the results of IHC and 28-gene signature-based molecular subtyping were highly consistent in luminal type, while the potential value of TNBC and HER2 enriched subtyping identified by the 28-gene signature needs to be further explored in the future.[Table: see text]