Chemotherapy response of breast cancer depends on HER-2 status and anthracycline dose intensity in the neoadjuvant setting

We evaluated the predictive value of a tumor's HER-2 status for chemotherap y response in the neoadjuvant setting and the effect of anthracycline dose intensity on this predictive value. HER-2 status was evaluated by immunoche mistry on microbiopsy before neoadjuvant chemotherapy (monoclonal antibody CB-11; Novocastra) in 39 patients (group A) treated with FEC50 (500 mg/m(2) 5-fluorouracil, 50 mg/m2 epirubicin, and 500 mg/m(2) cyclophosphamide) and 40 patients (group B) treated with FEC100 (500 mg/m(2) 5-fluorouracil, 100 mg/m(2) epirubicin, and 500 mg/m(2) cyclophosphamide), All tumors were sta ge II or noninflammatory stage LU adenocarcinoma, Overall response rate (OR ) was evaluated through ultrasound and mammographic measurements. Pathologi cal complete response was evaluated by tumor excision and axillary node res ection after six cycles of chemotherapy, Patient and tumor characteristics (age, tumor size, clinical nodal status, SBR grade, hormonal receptor statu s, and HER-2 expression) were similar in the two groups. In univariate anal yses, anthracycline dose was the only factor predictive of response (OR = 6 1.5% with FEC50; OR = 82.5% with FEC100; P = 0.038), When anthracycline dos e was correlated with HER-2 status, an OR of 73.9% was demonstrated in HER- 2- tumors (tumors without HER-2 overexpression), and an OR of 12.5% was dem onstrated in HER-2+ tumors (tumors,vith HER-2 with overexpression) in group A. In group B, an OR of 69.5% was demonstrated in HER-2- tumors, and an OR of 100% was demonstrated in HER-2+ tumors. There was no difference in OR f or HER-2- tumors treated with FEC50 or FEC100 (P = 0.74), On the other hand , erbB-2+ tumors treated with FEC100 had a significantly better OR than HER -2+ tumors treated with FEC50 (P = 0.0003), In a multivariate analysis, the most powerful predictive factor of OR was a conditional variable associati ng anthracycline dose with HER-2 status. Low-dose anthracycline and HER-2predicted a poor OR, low- or high-dose anthracycline and HER-2- predicted a n intermediate OR, and high-dose anthracycline and HER-2+ predicted a high OR. Our results merit additional studies, given the possibility for choosin g anthracycline dose according to a tumor's HER-2 status.