Concordance Of Intrinsic Subtyping And Risk Of Recurrence (Ror) Scores Between Matched Primary And Metastatic Tissue From Triple Negative Breast Cancer Trial (Tnt)

1019 Background: The majority of triple negative breast cancers are of basal-like subtype (BLBC). There is uncertainty about concordance of intrinsic subtypes and ROR scores by PAM50 between matched primary and metastasis samples. We sought to examine agreement of intrinsic subtypes and ROR groups using tissue in the TNT trial. Methods: TNT is a phase III, multicentre, randomized trial of carboplatin vs docetaxel in women with ER- PgR- HER2- metastatic/recurrent locally advanced breast cancer. Using Prosigna test on Nanostring nCounter, intrinsic subtyping was performed in a central laboratory on primary tumour (PT) from 216 patients, 66 positive lymph nodes (PLN) and 13 recurrent tissue samples (RC). The ROR-S (ROR based on subtype contents) and ROR-P (ROR based on subtype contents and proliferation index) were calculated using research-based PAM50 classifier (Parker JCO 2009). Agreement on classification was assessed by kappa statistics (k). Results: Of 216 PT, 175 (81%) were BLBC, 23 (11%) HER2enriched...