Prognostic Impact of Residual Disease After Neoadjuvant Chemotherapy in 648 Patients with Triple-negative Breast Cancer.

AIM In order to establish a new risk categorization system for triple-negative breast cancer (TNBC) after neoadjuvant chemotherapy, we analyzed a large database including more than 50% of all breast cancer cases nationwide. PATIENTS AND METHODS From a database of 39,570 primary breast cancer cases, 648 patients with TNBC were treated with neoadjuvant chemotherapy (2009-2011). The primary study end-point was the impact of residual tumor burden on survival. RESULTS Pathological complete response (pCR) was achieved in 199 patients; 449 patients had a non-pCR (pCR rate=30.8%). Stage ypT1 did not differ prognostically from ypT2, and likewise ypT3 not from ypT4 (in patients with N0 and N1-3 disease). Combined analysis of ypT1/2 and ypT3/4 yielded highly significant differences (p=0.000145). CONCLUSION A partial response still conveys a substantial survival benefit. There is no linear deterioration of prognosis according to residual tumor size. Post-neoadjuvant TNM stages ypT1 and ypT2, and ypT3 and ypT4 pairwise build uniform prognostic groups in TNBC, when there is no or low axillary lymph-node involvement.