HER2 amplification predicts breast cancer recurrence but not overall survival.

Abstract

Abstract Abstract #6070 INTRODUCTION: Human epidermal growth factor receptor-2 (HER2) amplification has been associated with an aggressive breast cancer phenotype. The aims of this study were: 1) to determine if a relationship between HER2 amplification and local recurrence or overall survival (OS) existed; and 2) to compare prognostic effects of HER2 amplification with race, age, TNM stage, Scarff-Bloom-Richardson (SBR) grade, and hormone receptor status.
 METHODS: Data were collected prospectively in our institutional review board approved breast center patient registry for patients with infiltrating ductal or infiltrating ductal-lobular mixed breast cancer; all other histologic types, including pure infiltrating lobular, were excluded from this analysis. Variables analyzed included race, age at diagnosis, tumor size, overall TNM stage, SBR grade, HER2 status, and hormone receptor status. Outcomes were defined as disease-free survival (local and distant) and OS. The prognostic effect of HER2 amplification on disease-free survival (DFS) and OS was assessed after adjusting for race, age, TNM stage, SBR grade, and hormone receptor status; Cox proportional hazards analysis was used in the multivariable analysis. A stepwise selection procedure was used in the multivariable analysis with p<0.10 required to allow a variable into the model and p<0.05 required to retain it in the final model. 
 RESULTS: Data were available for 1750 patients (mean age at diagnosis 60 years) diagnosed between January 2001 and July 2007; mean tumor size 1.8 cm, of which 384 (22%) were hormone receptor negative and 296 (17%) were HER2 amplified. Risk factors for DFS included HER2 amplification (Table 1), black race, increasing TNM stage, and negative hormone receptors. Risk factors for OS included black race, increasing TNM stage, and negative hormone receptors. HER2 amplification was associated with decreased disease-free survival (Fig 1a) but not OS (Fig 1b).
 
 
 
 CONCLUSIONS: Although HER2 amplification predicted disease-free survival, it did not predict OS in the multivariable analysis. A possible explanation for this finding is the increasing use of Trastuzumab for HER2 amplified tumors after relapse. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6070.