Response-Guided Neoadjuvant Chemotherapy for Breast Cancer

PURPOSE: We investigated disease-free survival (DFS) and overall survival (OS) after response-guided neoadjuvant chemotherapy in patients with early breast cancer. PATIENTS AND METHODS: We treated 2,072 patients with two cycles of docetaxel, doxorubicin, and cyclophosphamide (TAC) and randomly assigned early responders to four (n = 704) or six (n = 686) additional TAC cycles, and early nonresponders to four cycles of TAC (n = 321) or vinorelbine and capecitabine (NX; n = 301) before surgery. RESULTS: DFS was longer in early responders receiving TAC × 8 than in those receiving TAC × 6 (hazard ratio [HR], 0.78; 95% CI, 0.62 to 0.97; P = .026), and in early nonresponders receiving TAC-NX than in those receiving TAC × 6 (HR, 0.59; 95% CI, 0.49 to 0.82; P = .001). Exploratory analysis showed that DFS after response-guided chemotherapy (TAC × 8 or TAC-NX) was significantly longer (HR, 0.71; 95% CI, 0.60 to 0.85; P < .003), as was OS (HR, 0.79; 95% CI, 0.63 to 0.99; P = .048), than on conventional chemotherapy (TAC × 6). DFS was longer after response-guided chemotherapy in all hormone receptor-positive tumors (luminal A HR = 0.55, luminal B [human epidermal growth factor receptor 2 (HER2) negative] HR = 0.40, and luminal B [HER2 positive] HR = 0.56), but not in hormone receptor-negative tumors (HER2 positive [nonluminal] HR = 1.01 and triple negative HR = 0.87). Pathologic complete response did not predict these survival effects. pCR predicted an improved DFS in triple-negative (HR = 6.67), HER2-positive (nonluminal; HR 5.24), or luminal B (HER2-negative) tumors (HR = 3.74). CONCLUSION: This exploratory analysis suggests that response-guided neoadjuvant chemotherapy might improve survival and is most effective in hormone receptor-positive tumors. If confirmed, the response-guided approach could provide a clinically meaningful advantage for the neoadjuvant over the adjuvant approach in early breast cancer.