Abstract P5-16-11: Residual cancer burden (RCB) as a strong prognosis factor in breast cáncer (BC) patients treated with neoadjuvant chemotherapy (NACT) based on carboplatin, doxorubicin and taxanes

Purpose : Many pathologic response systems have been used since the arrival of NACT. The RCB is a standardized method, but not universally implemented (Symanns WF, et al. J Clin Oncol 2007) . The main objective is to apply the RCB and check its prognostic value in patients treated with platinum-based NACT with a long follow up. Methods: Patients diagnosed and treated with platinum based NACT are analyzed. They receive 4 cycles of carboplatin AUC 6 and doxorubicin 50 mg/m 2 , followed by either docetaxel 75 mg/m 2 (4 cycles) or weekly paclitaxel 80 mg/m 2 (8 doses), preoperatively. Pathological complete response (PCR) is defined as the absence of invasive tumor in the breast and axillary nodes, allowing the presence of DCIS. RCB system is applied and correlated with disease free survival (DFS) and overall survival (OS) according to Kaplan-Meier method; differences between curves with log rank test. Results: 109 patients (110 tumors) are included from Mar-2004 Mar-2009. Characteristics of patients and tumors: Mean age: 50.9 years (range 28-78 years); Premenopausal: 69 (62.7%). Median tumor diameter: 35 mm (0-90 mm); histology: ductal 85 (77.3%). Stage: IIa 46 (41.4%); IIb 40 (36%); IIIa-11 (10%); IIIb 12 (10.9%); IIIc 1 (0.9%). Phenotypes: luminal A 18 (16.4%); luminal B 36 (32.7%); HER2 luminal B 22 (20%); HER2 13 (11.8%); triple negative 21 (19.1%). Responses: pCR: 17.3%; pCR and RCB-I: 37.3%. Responses according to phenotypes: Surgery: lumpectomy 66 (60%). Follow up: DFS (median follow up 8,2 years (0,5-11,8)): 78,9%; OS (median follow up 8,6 years (0,8-11,41)). OS according to RCB: pCR: 94,7%; RCB-I: 86,4%; RCB-II: 76,6%; RCB-III: 58,8% (p 0,03). Conclusion : RCB is a strong prognostic factor, here validated for a platinum based CT with a long follow up. Additional data on OS according RCB in different phenotypes will be presented at the meeting. Citation Format: de Juan Ferre A, Mayorga Fernandez M, Alonso Bartolome P, Azcarretazabal Gonzalez-Ontaneda T, Munoz Cacho P, Mugica Estebanez M, Anchuelo Latorre J, Mata Velasco E, Saiz Isa L, Lopez Vega JM. Residual cancer burden (RCB) as a strong prognosis factor in breast cancer (BC) patients treated with neoadjuvant chemotherapy (NACT) based on carboplatin, doxorubicin and taxanes [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-16-11.