Triple-negative high-risk breast cancer derives particular benefit from dose intensification of adjuvant chemotherapy: results of WSG AM-01 trial

Abstract

BackgroundThis paper evaluates the prognostic and predictive impact of protein expression of various molecular markers in high-risk breast cancer (HRBC) patients with >9 involved lymph nodes, who received different chemotherapy dose-intensification strategies within a prospective randomized WSG AM-01 trial. Materials and methodsParaffin-embedded tumors from 236 patients, who were randomly assigned to dose-dense conventional chemotherapy with four cycles of E90C600 followed by three cycles of C600M40F600 every 2 weeks (DD) or a rapidly cycled tandem high-dose regimen with two cycles of E90C600 every 2 weeks followed by two cycles of E90C3000Thiotepa400 every 3 weeks (HD), were available for retrospective central pathological review (116 HD/120 DD). Expression of estrogen receptor (ER), progesterone receptor (PR), MIB-1, epidermal growth factor receptor, and Her-2/neu was evaluated immunohistochemically using tissue microarrays. Results were correlated with follow-up data and treatment effects by proportional hazard Cox regression models (including interaction analysis). ResultsAfter a median follow-up of 61.7 months, 5-year event-free survival (EFS) as well as overall survival (OS) rates for the 236 patients were significantly better in the HD arm: EFS: 62% versus 41% [hazard ratio (HR) = 0.60, 95% CI 0.43–0.85, P = 0.004]; OS: 76% versus 61% (HR = 0.58, 95% CI 0.39–0.87, P = 0.007). In multivariate analysis, HD, tumor size <3 cm, positive PR, negative MIB-1 staining, and grade 1/2 were associated with favorable outcome. Interaction analysis showed that regarding predictive effects, triple negative (ER/PR/Her-2/neu) and G3 tumors derived most benefit from HD. ConclusionTandem HD improves both EFS and OS in HRBC. This therapy effect may be partly attributable to superior efficacy in the subgroup of triple-negative tumors and/or G3 with their poor prognostic marker profile.