Prognostic factors in operable breast cancer treated with neoadjuvant chemotherapy: towards a quantification of residual disease.

OBJECTIVE: Neoadjuvant chemotherapy (NACT) allows for a more frequent use of breast-conservative surgery; it is also an in vivo model of individual tumor sensitivity which permits to determine new prognostic factors to personalize the therapeutic approach. METHODS: Between 2000 and 2012, 318 patients with primary invasive breast cancer were treated with a median of 6 cycles of NACT; they received either an anthracycline-based FEC 100 protocol (31.1%), or anthracyclines + taxanes (53.5%), with trastuzumab if indicated (15.4%). RESULTS: After a median follow-up of 44.2 months, the pathological complete response rate according to the classification of Chevallier et al. [Am J Clin Oncol 1993;16:223-228] was 19.3%, and overall (OS) and disease-free survival (DFS) at 10 years were 60.2 and 69.6%, respectively. Univariate analyses demonstrated that the Residual Disease in Breast and Nodes (RDBN) index was the most significant prognostic factor for OS (p = 0.0082) and DFS (p = 0.0022), and multivariate analyses mainly revealed that the residual tumor size, residual involved node number and post-chemotherapy Scarff-Bloom-Richardson (SBR) grading were the most significant prognostic factors. CONCLUSIONS: In a cohort of patients who were all homogeneously treated with some of the most common drugs for breast cancer, we demonstrate that NACT may provide additional prognostic factors and confirm the RDBN index. As this index allows for the prediction of survival with different breast cancer subtypes, we suggest that it should be calculated routinely to help clinicians to select patients who need adjuvant treatments.