Abstract
Breast cancer (BRCA) is the most common cancer among women and is the second leading cause of cancer death in women. In this study, we developed a 9-gene prognostic signature to predict the prognosis of patients with BRCA. GSE20685, GSE42568, GSE20711, and GSE88770 were used as training sets. The Kaplan-Meier plot was constructed to assess survival differences and log-rank test was performed to evaluate the statistical significance. The overall survival (OS) of patients in the low-risk group was significantly higher than that in the high-risk group. ROC analysis indicated that this 9-gene signature shows good diagnostic efficiency both in OS and disease-free survival (DFS). The 9-gene signature was further validated through GSE16446, GSE7390, and TCGA-BRCA datasets. We also established a nomogram that integrates clinicopathological features and 9-gene signature. The analysis of the calibration plot showed that the nomogram has good prognostic performance. More convincingly, real-time reverse transcription-polymerase chain reaction (RT-PCR) results indicated that the protective prognostic factors in BRCA patients were downregulated, whereas the dangerous prognostic factors were upregulated. The innovation of this article is not only constructing a prognostic gene signature, but also combining with clinical information to further establish a nomogram to better predict the survival probability of patients. It is worth mentioning that this signature also does not depend on other clinical factors or variables.