A Proposal to Redefine Pathologic Complete Remission as Endpoint following Neoadjuvant Chemotherapy in Early Breast Cancer.

Many analyses of the efficacy of neoadjuvant treatment (NAT) for early breast cancer including a meta-analysis derived from 10 randomized trials came to the conclusion that patients who would achieve pathologic complete response (pCR) following NAT would experience significant improvement in disease-free and overall survival (OS). Thus, pCR was proposed as a surrogate endpoint for OS, with pCR representing a robust prognostic marker for survival at an individual level. In the current analysis, we argue that OS following NAT-induced pCR might have reflected the initial prognosis of patients mainly defined - among other factors - by the initial pathological lymph node status while being largely independent on the type of administrated treatment, thus pleading against the pCR surrogacy hypothesis. We therefore propose to redefine pCR as a surrogate endpoint of NAT trials by the involvement of additional biologic parameters.