Inter-pathologist agreement of residual cancer burden (rcb) assessment in breast cancer after treatment with preoperative chemotherapy

Abstract

576 Background: The objective of the study was to evaluate the agreement of residual cancer burden (RCB) measurements—a method to quantify residual disease (RD) after preoperative chemotherapy—when assessed by different pathologists. Methods: One hundred cases with residual in situ, invasive, or metastatic carcinoma were selected from a previous published series. Pathology slides and reports were reviewed independently by four pathologists, including a fellow, a visitor, and two faculty at MDACC. Percent tumor cellularity, size of tumor bed, size of largest axillary metastasis and number of involved nodes were assessed separately by each pathologist and RCB categories were assigned to each case following calculation of the RCB index (www.mdanderson.org/breastcancer_RCB): RCB-0 corresponds to pCR, RCB-I to minimal RD, RCB-II to moderate RD and RCB-III corresponds to extensive RD. Inter-pathologist agreement in the assessment of the continuous RCB index and its components was evaluated based on the overall ...