In vivo chemosensitivity-adapted preoperative chemotherapy in patients with early-stage breast cancer: the GEPARTRIO pilot study

Background: Response to the first two cycles of preoperative chemotherapy might differentiate subgroups of breast cancer patients with high or minimal chances for a pathologic complete response (pCR) and may be used as an in vivo chemosensitivity test. Methods: Breast cancer patients were treated with two cycles of TAC (docetaxel 75 mg/m(2), doxorubicin 50 mg/m(2), cyclophosphamide 500 mg/m(2) every 21 days). Patients whose tumors showed a response received four more cycles. Patients whose tumors did not respond were randomized to four additional cycles TAC or NX (vinorelbine 25 mg/m(2) days 1 and 8, capecitabine 2000mg/m(2) days 1-14, every 21 days). The primary end point was pCR at surgery. Results: Two hundred and eighty-five patients showed a clinical response, in 73.0% after two cycles, in 88.4% at surgery, and a pCR was seen in 17.9%. Breast conservation was possible in 72.2%. Responding patients obtained a pCR in 22.6% whereas non-responding patients reached a pCR in 7.3% and 3.1% with TAC or NX, respectively. Grade III/IV neutropenia and febrile neutropenia were observed during TAC in 70.2% and 13.5%, respectively. Significantly less toxicity were observed with NX. Conclusion: Early response to TAC can reliably identify patients with a high chance of achieving a pCR. New effective treatments need to be explored for patients without an early response.