HER2 amplification does not alter outcome in small (≤1 cm) tumors.

Abstract

Abstract Abstract #6058 INTRODUCTION: Amplification of human epidermal growth factor receptor-2 (HER2) has been associated with an aggressive clinical phenotype, however the management of patients with small tumors (<1 cm) that amplify HER2 is controversial. The goals of this study were: 1) to describe characteristics of HER2 amplified tumors based on tumor size, and 2) compare outcomes among 4 groups based on tumor size (small tumors <1 cm or large tumors >1 cm) and HER2 amplification (+ or -.)
 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. There were 770 patients with N0 tumors who were diagnosed between January 2001 and April 2005 (prior to treatment of HER2 amplified tumors with Trastuzumab). Categorical variables were compared using the Chi-squared test; outcomes were estimated using the Kaplan-Meier method and the log-rank test.
 RESULTS: At 4 years, estimated disease free interval was 97% in small HER2- tumors, 92% in large HER2- tumors, 91% in small HER2+ tumors, and 86% in large HER2+ tumors.
 
 At 4 years, breast cancer specific survival was 97% in small HER2- tumors, 92% in large HER2- tumors, 91% in small HER2+ tumors, and 86% in large HER2+ tumors.
 CONCLUSIONS: In our series, larger as opposed to smaller HER2+ tumors tended to be of higher histologic grade (SBR), and showed a trend toward more frequent lymphovascular invasion (LVI) and negative hormone receptor status. In small tumors, HER2 amplification did not predict recurrence-free survival or breast cancer disease specific survival at 4 years. The survival curves do show trends towards worsening outcomes for small tumors with HER2 amplification; these trends may show significance with additional follow-up. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6058.