HER2 Gene Amplification: The Most Important Independent Prognostic Factor in Patients with Stage II Breast Cancer
Pingchuan Zhang, Eduardo Castro-Echeverry, Sheila M Dobin, Arundhati Rao. Scott and White Memorial Hospital, Temple, TX; Texas A&M Health Science Center, College Station, TX
Background: HER2 gene amplification in invasive breast cancer is generally associated with poor prognosis. However, the long-term significance of HER2 status using the 2009 ASCO/CAP guidelines, with emphasis on genetic heterogeneity, has not been well established in stage II breast cancer.
Design: A retrospective chart review was performed on patients diagnosed with Stage II Breast Cancer in 2002. HER2 was evaluated by fluorescence in situ hybridization (FISH) and the cases were categorized per 2009 ASCO/CAP guidelines as amplified, heterogeneous genetic heterogeneity (GH), and non-amplified. Covariates included age, Nottingham combined grade, Estrogen receptor (ER) and progesterone receptor (PR) status. Cox Proportional Hazards (PH) regression modeling and Kaplan-Meier Survival Curves were used to determine independent predictors of tumor free survival.
Results: Of 347 registered breast cancer cases from 2002, 70 were stage II patients with HER2 data. HER2 gene amplification status is as follows: 7 cases (11.4%) amplified, 4 (5.7%) GH, 59 (84.3%) not amplified. After adjusting for age and ER/PR status, amplified HER2 status was the most important independent prognostic factor by Cox PH (HR 4.7, 95%CI 1.5-14.8, p= 0.009). No significant difference (P=0.37) in prognosis was found between the HER2 non amplified group and the GH group (Figure 1). Compared to the non amplified and GH groups, the patients with HER2 amplification have worse prognosis (P= 0.035) (Figure 2). Age, ER status, PR status and Nottingham combined grade were not significantly associated with tumor free survival in this cohort.
Conclusions: HER2 amplification status is the single, independent, and most important prognostic factor in stage II breast cancer in our study while HER2 GH is not correlated with clinical outcome. With regard to the prognostic significance of HER2 amplification and the clinical relevance of HER2 heterogeneity, a large size, preferably randomized clinical trial, is needed.
Monday, March 19, 2012 11:45 AM
Platform Session: Section B, Monday Morning