Using Response to Primary Chemotherapy to Select Postoperative Therapy: Long-Term Results from a Prospective Phase II Trial in Locally Advanced Primary Breast Cancer

PurposeThis study sought to quantify the extent of downstaging after preoperative chemotherapy for stage III breast cancer, to assess the feasibility of breast-conserving therapy (BCT) after preoperative chemotherapy, to determine the effectiveness of this multimodal treatment as measured by disease-free survival (DFS) and overall survival (OS), and to evaluate toxicities.Patients and MethodsPatients were treated with 4 preoperative courses of 5-fluorouracil, doxorubicin, and cyclophosphamide (FAC). They were then evaluated for response to go to mastectomy or BCT. After local therapy, patients with an excellent response were treated with 4 additional cycles of FAC, whereas patients with a moderate response received 4 cycles of MV (methotrexate and vinblastine). A total of 203 patients were registered; 194 patients (96%) underwent surgery after chemotherapy.ResultsThe 5-year OS and progression-free survival rates were 89.8% and 81.6%, respectively, for patients with an excellent response to therapy compared with 67.2% and 63.5%, respectively, for patients with a moderate response and 55.3% and 48.8%, respectively, for patients considered nonresponders (P = .0005 for OS; P < .0001 for DFS). Cytopenia, nausea/vomiting, and stomatitis were the most common toxicities. Preoperative chemotherapy with FAC downstaged 88.6% of patients, and BCT was possible in > 25%.ConclusionResponse to preoperative chemotherapy was a prognostic factor in improved long-term survival.