Prognostic and predictive value of topoisomerase II alpha in a randomized trial comparing CMF to CEF in premenopausal women with node positive breast cancer (NCIC CTG MA.5)

Abstract

533 Background: It has been suggested that Topoisomerase II alpha (TOP2A) status rather than Her-2/neu status may predict response to anthracycline chemotherapy in breast cancer. Methods: In MA.5, 710 premenopausal women with node positive breast cancer were randomized to receive adjuvant CEF (epirubicin 60 mg/m2 & 5-FU 500 mg/m2 both IV, days 1 & 8, and cyclophosphamide 75 mg/m2 p.o. days 1 through 14); vs CMF (methotrexate 40 mg/m2 & 5-FU 600 mg/m2 both IV days 1 & 8 and cyclophosphamide 100 mg/m2 p.o. days 1 through 14), all for six 28-day cycles. Tissue microarrays (TMAs) were constructed from paraffin embedded specimens from 447 (63%) of these patients. TOP2A was measured by fluorescence-in-situ hybridization (FISH), classifying tumors into 3 groups by TOP2A/CEP 17 ratios: amplified (Amp) if ratio ≥2; deleted (Del) if ratio < 0.8; normal (N) if ratio 0.8 to 2. Cox models assessed interaction between treatment and TOP2A, adjusting for age, nodal status, ER, HER-2/neu status, grade, surgery and tumor size. Results: Thirty-one patients (6.9%) had tumours with Del TOP2A; 53 (11.9%) with Amp TOP2A; and 353 (81.2%) with N TOP2A. 5-year disease-free survival (DFS) was 48%, 51%, and 61% for patients with Del, Amp and N TOP2A respectively (p=0.22 adjusted global test). 5-year overall survival (OS) was 55%, 61% & 75% for patients with Del, Amp, and N TOP2A (p=0.67 adjusted global test). HRs for DFS and OS by treatment and TOP2A are presented in the table . Conclusions: TOP2A status was a significant predictive factor for benefit from CEF treatment for OS. Although there was a trend for TOP2A status predicting improved DFS with CEF, the test for interaction was not significant. In adjusted analysis TOP2A did not reach significance as a prognostic factor for DFS or OS. (This study was supported by the Canadian Breast Cancer Research Alliance (CBCRA), the National Cancer Institute of Canada (NCIC) and the Canadian Cancer Society.) [Table: see text] [Table: see text]