Evaluation and Validation of Neo-Adjuvant Response Index (NRI) and It's Correlation with Various Predictive Biomarkers and RECIST in Locally Advanced Breast Cancer.

Background: Response evaluation following neo-adjuvant chemotherapy in breast cancer is usually done without taking in to account the axillary response and the available tools like 'response evaluation criteria in solid tumors' (RECIST) have this limitation. These criteria rely solely on the response observed in the primary tumour. Neoadjuvant response index is one such attempt to have a comprehensive assessment of response both in the primary tumour and the axilla. Methods: 30 cases of locally advanced breast cancer (LABC) were assessed for response using 'Neo-adjuvant Response Index'. The index always gives score between '0' (no response or progressive disease) and '1' (pathological complete response i.e. no invasive tumor in breast as well as axilla). This index includes axillary response as well and provides a spectrum of response rather than dividing patients into simply responders and non-responders . Results: Mean reading of index was found to be 0.2925 in this study. Three patients achieved an index of 1. This index correlates significantly with the existing scales for assessing response. Hormone negative tumors were found to be more chemo responsive with higher rates of pathological complete response (pCR) while ER/PR + Her2- tumors showed a very poor response to NACT. Conclusions: Based on the observations of the present study it may be submitted that Neoadjuvant Response Index (NRI) is a reliable and simple tool that can serve as a comprehensive and accurate method of assessing response to neo-adjuvant chemotherapy as it takes in to consideration both the tumor and axillary response unlike the existing RECIST, binary system (responders are those with greater than 50 % reduction), RCB method and the available biomarkers. This study being first of it's kind in Indian population, in spite of it's limitations, could prove to be a launching ground for further reasearch and contribute substantially to the evidence base. [ABSTRACT FROM AUTHOR]