Utility of the CPS plus EG staging system in hormone receptor-positive, human epidermal growth factor receptor 2-negative breast cancer treated with neoadjuvant chemotherapy

Background: Pathologic complete response after neoadjuvant chemotherapy (NACT) correlates with overall survival (OS) in primary breast cancer. A recently described staging system based on pre-treatment clinical stage (CS), final pathological stage (PS), estrogen receptor (ER) status and nuclear grade (NG) leads to a refined estimation of prognosis in unselected patients. Its performance in luminal type breast cancers has not been determined. This study investigates the clinical utility of this CPS + EG score when restricted to hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) patients and compares the results to a cohort of unselected patients. Methods: The CPS + EG score was calculated for 6637 unselected patients and 2454 patients with HR +/HER2- tumours who received anthracycline/taxane-based NACT within 8 prospective German trials. Results: Five-year disease-free survival (DFS) and OS were 75.6% and 84.1% for the unselected cohort and 80.6% and 87.8% for theHR +/HER2- subgroup, respectively. The CPS + EG system distinguished different prognostic groups with 5-year DFS ranging from 0% to 91%. The CPS + EG system leads to an improved categorisation of patients by outcome compared to CS, PS, ER or NG alone. When applying the CPS + EG score to the HR +/HER2- subgroup, a shift to lower scores was observed compared to the overall population, but 5-year DFS and OS for the individual scores were identical to that observed in the overall population. Conclusions: InHR +/HER2- patients, the CPS + EGstaging system retains its ability to facilitate a refined stratification of patients according to outcome. It can help to select candidates for post-neoadjuvant clinical trials in luminal breast cancer. (C) 2015 Elsevier Ltd. All rights reserved.