Validation of a Novel Staging System for Disease-Specific Survival in Patients With Breast Cancer Treated With Neoadjuvant Chemotherapy

Abstract

Purpose We previously described a novel breast cancer staging system for assessing prognosis after neoadjuvant chemotherapy on the basis of pretreatment clinical stage (CS), estrogen receptor status (E), grade (G), and post-treatment pathologic stage (PS). This clinical-pathologic stage (CPS) + EG staging system assigned and summed points for each factor, allowing for better determination of breast cancer–specific survival than CS or PS alone. The current study was undertaken to validate this staging system using internal and external cohorts. Methods We identified an internal cohort of 804 patients treated with neoadjuvant chemotherapy at our institution from 2003 to 2005 and an external cohort of 165 patients treated at another institution. Clinicopathologic characteristics, treatment regimens, and patient outcomes were assessed. Outcomes were stratified by CPS + EG score. Results Five-year disease-specific survival (DSS) for the internal cohort was 77% (95% CI, 72 to 82) at a median follow-up of 3.4 ye...