BACKGROUND: A previously published prospective randomized phase 3 trial showed 
that administration of 24 weeks of primary systemic chemotherapy (PST) with 
paclitaxel and FEC(75) (fluorouracil, epirubicin, cyclophosphamide) concurrently 
with trastuzumab in patients with HER2-positive primary breast cancer resulted 
in a 60% pathologic complete response rate (PCR) with no associated severe 
cardiac toxicity. The purpose of this study was to review the efficacy and 
safety of a similar regimen outside the setting of a clinical trial.
METHODS: Patients with HER2-positive breast cancer (defined as either 
immunohistochemical 3+ or fluorescence in situ hybridization-positive) that had 
received 24 weeks of neoadjuvant trastuzumab concurrently with taxane and 
anthracycline-based chemotherapy between 2004 and 2006 were included in the 
analysis. PST chemotherapy consisted of paclitaxel (80 mg/m(2)) weekly for 12 
weeks followed by 4 cycles of FEC(75) (500 mg/m(2), 75 mg/m(2), and 500 mg/m(2), 
respectively).
RESULTS: Forty patients were identified. The median age was 48 years (range, 
29-81). In all, 60% of patients had stage III disease and 4 had inflammatory 
breast cancer. The PCR rate was 55% (95% confidence interval [CI], 38.5%-70.7%). 
At a median follow-up of 19 months. 5 patients had a recurrence, of which 4 did 
not achieve a PCR. No severe cardiac events were observed.
CONCLUSIONS: Stage II and III HER2-positive breast cancer patients achieved a 
high rate of PCR with trastuzumab given concurrently with paclitaxel and FEC(75) 
chemotherapy. No severe cardiac events were observed with the regimen. The data 
concur with the results of a previously published trial.