Omission of Chemotherapy in HR+/HER2− Early Invasive Breast Cancer Based on Combined 6-IHC Score? (original) (raw)

1. This study involves the clinical determination of whether HR + /HER2 − early BC needs chemotherapy and seeks for a more accurate and cheaper method. 2. Select genes related to BC invasion and metastasis, and establish a scoring model for their immunohistochemical results by Cox regression. 3. The scoring model can well judge the prognosis of HR + /HER2 − BC patients. Purpose: Current methods of judging whether HR + /HER2 − breast cancer (BC) require adjuvant therapy, such as Ki67 and multigene prognostic tests, cannot balance accuracy with the price most patients can afford. Methods: A retrospective analysis of 330 HR + /HER2 − BC patients was conducted. Six BC-related genes (Cathepsin L2, MMP11, CyclinB1, Aurora A, Survivin, and Ki67) were screened using univariate and multivariate COX regression, and correlate clinical follow-up with immunohistochemical expression (designated as 6-IHC). All the included patients were divided randomly at a 7:3 ratio into training and testing cohorts. The cutoff prognosis index (PI) of 6-IHC was determined by multivar iate Cox r isk regression analysis after calculating the PI of each patient in training cohort and confirmed in testing cohort. Kaplan-Meier (KM) method was used to analyze Disease-free survival (DFS) and overall survival (OS). Six-IHC score and other factors associated with survival benefit of adjuvant chemotherapy were compared with Ki67 index. Results: The receiver operating characteristic curve analysis showed that the patients can be divided into 6-IHC score "High" and "Low" risk groups. The 8-year DFS and OS of the KM curves showed that chemotherapy did not significantly improve the DFS in the 6-IHC score "Low" risk group (P = 0.830), but significantly improved the DFS in the 6-IHC score "High" risk group (P = 0.012). Conclusions: Combined 6-IHC score could be a reliable tool in predicting cancer-specific recurrences and survival in HR + /HER2-breast cancer patients, with additional advantages over using immunohistochemical expression of Ki67.