[Responses to primary systemic therapy for breast cancer as assessed by hormone receptor and HER2 status]

The aim of this study was to investigate responses to primary systemic therapy (PST) for breast cancer, by hormone receptor (HR) and HER2 status. This study included 107 women with T>3 cm and/or node-positive breast cancer who received PST at this department between March 2004 and January 2009. Treatment with epirubicin and cyclophosphamide (EC) followed by docetaxel (DTX) therapy was undertaken up to December 2005. From January 2006, EC followed by weekly paclitaxel (PTX) with or without trastuzumab (T) therapy was performed. From February 2008 and thereafter, the EC-PTX-T therapy was continued in HER2-positive patients, whereas the preceding EC-DTX therapy was administered in HER2-negative patients. Clinical responses of the 107 patients (56 were treated with EC-DTX, 37 with EC-PTX, and 14 with EC-PTX-T) were as follows: CR was achieved in 18 patients, PR in 74 patients, SD in 12 patients, and PD in 3 patients, with a response rate of 86. 0%. Histologically, 14 patients(13. 2%)had pathological CR(pCR)in a limited sense. When these patients were further divided according to HR status, those positive for both estrogen receptor (ER) and progesterone receptor (PgR) accounted for 1. 8%, those positive for ER and negative for PgR accounted for 5. 3%, and those negative for both ER and PgR accounted for a significantly higher percentage of 40. 0% (p<0. 0001) . By HER2 status, pCR was achieved at a significantly higher rate (47. 8%) of HER2-positive patients, compared to 3. 6% of HER2-negative patients (p<0. 0001). Common adverse events included Grade 3/4 leukopenia (57. 9%), neutropenia (67. 3%), and Grade 3 febrile neutropenia (11. 2%). The results show that a higher pCR rate can be expected after PST in HR-negative patients and HER2-positive patients. HER2-positive patients would particularly benefit from preoperative anthracycline chemotherapy followed by a taxane combined with trastuzumab.