Characterization of HER2/neu and topoisomerase IIa status by FISH in locally advanced breast cancer

Background. HER2/neu encodes a receptor related to breast cancer pathogenesis and topoisomerase IIa is an enzyme involved in response to anthracycline chemotherapy. The aim of this study is to analyse HER2/neu and topoisomerase IIa in a homogenous series of 49 patients with locally-advanced breast cancer (LABC) to determine their status and predictive value with respect to response to treatment. Material and methods. Paraffin-embedded tissues samples from patients with LABC (prior to their neoadjuvant chemotherapy programme) were analysed using the FISH technique. Results. HER2 amplification was noted in 29% of cases of which 77% presented amplification in the topoisomerase IIa gene, 15% had deletion and 8% did not show any aberration in topoisomerase IIa status. Conclusions. These preliminary analyses show a correlation between HER2 amplification and topoisomerase IIa status (92%), and suggest that patients with non-amplified HER2/neu or topoisomerase IIa have better response and have and increase (albeit not statistically significant) in disease- free survival (DFS). However, the limited numbers of patients in the study preclude definitive conclusion regards the value of these genes in predicting patient response to anthracycline-based chemotherapy.