259PD - The 12-Gene Dcis Score Assay and Quantitative Er, Pr, and Her2 Across Histologic Subtypes: Experience in the First 2 Years

Abstract

ABSTRACT Aim: The 12-gene DCIS Score has been validated to predict 10yr risk of local recurrence (DCIS or invasive) (Solin et al, JNCI, 2013). Here we report the Clinical Laboratory experience in the first 2 yrs of assay availability for the score results, quantitative gene expression and results of the assay across histologic subtypes. Methods: 3045 patient (pt) samples from 12/11 to 1/14 were processed for DCIS score. The DCIS score is based on the validated algorithm using 7 of 16 cancer-related genes from the 21-gene assay. Low, intermediate, and high risk groups are defined as scores of Results: Of 3045 samples, 2264 (74%) were excisions and 781 (26%) were cores; median age was 60y (21-94). The mean DCIS Score was 29 (0-97) with a mean score result of 29 for excisions and 29 for cores. 2064 (68%) were low, 495 (16%) were intermediate, and 486 (16%) were high. Mean ER, PR, and HER2 levels were 9.6, 7.5, and 9.9, respectively, and similar between excisions and cores. A range of DCIS Score results were observed for each histologic subtype with the highest mean values observed in samples with >50% comedo necrosis (mean = 47) and solid (mean = 34) subtypes, although none of the scores were in the high risk category. Table: 259PD . Tumor type Distribution (%) Mean DCIS Score (range) Mean ER Mean PR Mean HER2 Cribriform 1202 (39) 22 (0-90) 9.9 7.8 9.7 Solid 1053 (35) 34 (0-96) 9.4 7.2 9.9 DCIS with ≥50% comedo necrosis 345 (11) 47 (0-97) 8.4 6.3 10.2 Papillary 281 (9) 17 (0-90) 10.9 8.6 9.6 Micropapillary 146 (5) 26 (0-88) 9.4 7.3 10.0 Apocrine 11 (0.4) 26 (4-53) 7.6 6.0 9.7 Conclusions: In the first 2 yrs, there were > 3000 samples submitted for the 12-gene DCIS score assay. The proportion of score results that were low, intermediate and high was similar to the validation study. The mean DCIS score result between core bx and excision was also similar supporting assay use on cores. The overall experience shows that the score results reflect underlying biology differently than histology and are informative for guiding treatment decisions. Disclosure: All authors have declared: Genomic Health, Inc. - employee and stock ownership