Abstract P6-03-02: Independent evaluation of prognostic value of residual cancer burden (RCB) score on disease free and overall survival of breast cancer patients treated with neoadjuvant systemic treatment at a single institution
Authors: Balic M , Mueller DH , Hammer R , Gumpoldsberger M , Suppan C , Posch F , Stoeger H , Dandachi N , Prein K , Hauser H , Lax S 
Published: February 2018

Introduction: Among the various approaches to measure response to neoadjuvant chemotherapy in breast cancer patients a significant relationship to overall (OS) and disease-free survival (DFS) has been recently demonstrated for the residual cancer burden (RCB) score. The calculated RCB- index provides additional prognostic information independently of TNM categories and stage, respectively[1]. The goal of our study was to validate the prognostic impact of the RCB score for OS and DFS on a cohort of patients selected for neoadjuvant treatment and treated either with chemotherapy with or without Her2 targeted therapy or endocrine therapy. We hypothesised that accross all histological breast cancer subtypes, the RCB-score will show significant impact on OS and DFS.

Methods: All surgical specimens (n =212) were processed according to the same protocol in a single institution. The RCB score was calculated according to Symmans et al. using the MD Anderson website. Pathologic complete remission is designated RCB 0, residual disease is based on its extent categorized as RCB I-III. Additional information such as histological and molecular subtypes, therapy regimen, as well as follow up information were collected prospectively from paper based patient files. The impact of the RCB score on OS and DFS were estimated with Kaplan-Mayer curves were compared by using long rank test statistics.

Results: The RCB score showed a significant correlation to DFS (p=0.000006) and OS (p=0.000306) The correlation between molecular subtypes (Luminal A, luminal B, Her2 positive and triple negative) and neoadjuvant treatment is ongoing and will be presented at the meeting.

Conclusion: We were able to show a general prognostic value of the RCB-Score in a series of 212 patients with neoadjuvant treatment, without consideration of the histological and molecular subtypes and adjuvant treatment. We were further able to confirm the reproducibility of the RCB Score by a standardized pathological procedure at a single institution. Further independent evaluation of the histological and molecular subtypes as well as the therapy regimens is ongoing.

[1] Loibel S.;How much information do we need to know after neoadjuvant Chemotherapy for Breast Cancer; American Society of Clinical Oncology, 24.Feb.2017.

Citation Format: Balic M, Mueller DH, Hammer R, Gumpoldsberger M, Suppan C, Posch F, Stoeger H, Dandachi N, Prein K, Hauser H, Lax S. Independent evaluation of prognostic value of residual cancer burden (RCB) score on disease free and overall survival of breast cancer patients treated with neoadjuvant systemic treatment at a single institution [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-03-02.