Abstract P1-14-12: Validation of residual cancer burden index (RCB) as a prognostic tool in patients with early breast cancer (EBC) treated with neoadjuvant chemotherapy (NAC): Comparison of RCB and Miller & Payne system (M&P)

Abstract

Abstract Pathological evaluation of response after NAC is a controversial issue. M&P has been for years the most widely employed score. Recently RCB index, a new system including axillary evaluation, seems to improve prognostic discrimination. PURPOSE: The aim of this study was to validate the RCB index as a method to define prognosis in a reallife cohort of EBC patients treated with NAC and compare it to M&P system. METHODS: We performed a retrospective analysis of our database. Patients with stage I-III considered candidate for NAC between January 2003 and August 2011 were included. RCB and M&P were calculated as previously published. Hormone receptor expression (RH), and Her2 were assessed following international guidelines. The Harell c-index and Roc curves were used to compare the prognostic value of RCB and M&P. Clinical, therapeutic and pathological data were obtained from medical records. A correlation with disease-free survival (DFS) and overall survival (OS) was done using the Kaplan-Meier method and Cox regression model. RESULTS: 333 patients were included in this study. Distribution of breast cancer subtypes was: luminal 50.9%, Her2+ 31% and triple negative 18.1%. Mean tumour size was 42.3 mm. The majority of the patients had histhological grade II-III tumours (87.3%), with N stage 0-1 (97.3%). 87.4% received anthracycline and taxane-based NAC, associated to trastuzumab in her 2+ patients. Pathological complete response was 14% for the global population, being 30% for TN and 21.3% Her2+ subtypes. With a median follow-up of 56.3 months, DFS and OS at 5 years were as follows: RCB-0 93.6% and 97.9%, RCB-I 84.2% and 98.2%, RCB-II 79.1% and 89.5%, RCB-III 38.3% and 63.6%. Harell c-index value of RCB was statistically superior to M&P in both DFS (0.80 vs 0.68, p= 0.001) and OS (0.87 vs 0.69, p<0.001 ). This superiority value of RCB was consistent among all breast cancer subtypes. CONCLUSION: RCB index is as more accurated prognostic score to predict DFS and OS compared to M&P. Citation Format: Pons V, BurguÉs O, PÉrez-Fidalgo JA, MartÍnez MT, Pinilla K, Bermejo B, Lluch A. Validation of residual cancer burden index (RCB) as a prognostic tool in patients with early breast cancer (EBC) treated with neoadjuvant chemotherapy (NAC): Comparison of RCB and Miller & Payne system (M&P). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-14-12.