Hormone receptor discordance between local and central pathology with RT-PCR analysis: Results from multicenter Phase III WSG-PlanB trial.

e11555 Background: Discordances between local and central pathology regarding ER, PR, and HER2 status may occur at varying frequencies, which may be attributable to technical factors (tissue handling, inter-observer variability) or to underlying disease heterogeneity. Our aim was to analyze local and central ER/PR status among samples acquired in a randomized clinical trial for associations with clinical and pathological parameters. Methods: PlanB accrued 3,198 patients with primary HER2- breast cancer to (i) optimize prognostication using Recurrence Score (RS) and (ii) compare adjuvant anthracycline-free (docetaxel/cyclophosphamide) to anthracycline-containing chemotherapy (EC-Doc). Recently, WSG-Plan B provided first prospective phase III survival data for Oncotype DX with 98% 3y EFS for low and intermediate risk RS. Patients were entered based on local immunohistochemistry (IHC) but also centrally tested (ER/PR, grade, Ki67). Here, discordant cases were identified, rechecked, and analyzed regarding cli...