Abstract PS2-21: Analysis of the clinical applicability of modified residual cancer burden system in evaluating the pathological response of breast cancer after neoadjuvant treatment
Authors: Ma Yanqi , Liu Yueping 
Published: February 2021

Abstract
Objective: To study the related factors affecting the residual cancer burden (RCB) after neoadjuvant therapy for breast cancer, and to modify the residual cancer burden system for patients after neoadjuvant therapy. To analyze the modified residual cancer burden system in predicting prognosis in patients with different molecular types. Methods: A retrospective analysis was conducted on 1274 patients who were diagnosed with invasive carcinoma of the breast by preoperative coarse needle aspiration pathology from January 2009 to December 2017, and who underwent surgical resection after neoadjuvant therapy. Follow-up was 1186. From 2009 to 2016, 837 patients were randomly assigned to the training set, and combined with HER2 expression before neoadjuvant therapy for revised residual cancer burden system (HER2-RCB). In 2017, 349 patients formed a verification set, which was used to verify the effectiveness of the analytical model. In this study, SPSS21.00 was used for statistical analysis, Spearman was used for correlation analysis, Hosmer-lemeshow test constructed model calibration degree, ROC curve was used to evaluate the efficiency comparison, Kaplan-Meier and Cox were used for survival analysis, P&lt;0.05 was statistically significant. Results: All patients in this study were female, with an average age of 50+8.7 years (24-86 years). Spearman correlation analysis showed that RCB classification was positively correlated with ER, PR expression, clinical stage, and age before neoadjuvant therapy (P&lt;0.05), and negatively correlated with KI67, HER2 expression before neoadjuvant therapy, postoperative vascular tumor thrombus and lymph node metastasis (P&lt;0.05). In the training set and validation set groups, the HER2-RCB classification has a good and consistent calibration between the predicted value of the patient's overall survival (OS) and disease-free survival (DFS) risk and the actual observed value. Sexuality is high (P&gt;0.05), and the prognostic risk stratification of patients is higher than RCB classification (AUC=0.782, 0.699; 0.819, 0.719). According to the molecular types of breast cancer, and compared with other molecular typing, the differences that the RCB classification predicts the OS of patients with HER2 over-expression and Luminal B HER2 positive breast cancer were statistically significant (P&lt;0.05), but there was no statistically significant difference in DFS (P&gt;0.05), while the differences that the HER2-RCB classification predicts OS and DFS in patients with HER2 over-expression, and Luminal B HER2-positive breast cancer were statistically significant (P&lt;0.05). Conclusions: HER2-RCB classification is more accurate than RCB classification in predicting prognosis, and the prediction of recurrence and metastasis risk in patients with HER2 over-expression and Luminal B HER2 positive breast cancer is better than RCB classification. It is suggested that HER2-RCB classification has better clinical applicability.Key words: Neoadjuvant therapy, Residual cancer burden, Pathologic complete response, Human epidermal growth factor receptor 2, Molecular type
Citation Format: Yanqi Ma, Yueping Liu. Analysis of the clinical applicability of modified residual cancer burden system in evaluating the pathological response of breast cancer after neoadjuvant treatment [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS2-21.