Abstract: Objective To investigate the relationship between the expression of immune-related LncRNA and the prognosis of breast cancer, and to construct an immune-related LncRNA risk model for predicting prognosis of breast cancer. 
Methods The transcriptome data and clinicopathological information of breast cancer from the TCGA public database were downloaded, and the expression matrix of breast cancer data was extracted using Perl software. Immune-related LncRNA was extracted using the co-expression method via R language, and the prognosis-related LncRNA was screened by univariate and multivariate Cox regression analyses. According to the optimal AIC value, immune-related LncRNA for predicting prognosis was determined to construct a prognostic risk model, and the patients were divided into low-risk group and high-risk group according to the risk value. Kaplan-Meier analysis method was used for survival analysis and survival curves of patients in the two groups were drawn. ROC curve was used to evaluate the accuracy of the prognostic risk model, while univariate and multivariate Cox regression analyses were used to evaluate the correlation between the prognostic risk model and tumor prognosis. 
Results A total of 1 041 breast cancer samples were downloaded from TCGA data, and 14 142 LncRNA expression profiles were extracted. In addition, 644 immune-related LncRNAs were obtained by co-expression method. Fourteen LncRNAs were screened by the univariate Cox regression analysis of immune-related LncRNAs. The 14 LncRNAs were subjected to multivariate Cox regression analysis, and 6 LncRNAs were screened according to the optimal AIC value to construct a prognostic risk model. Patients were divided into low-risk and high-risk groups according to the risk value. Survival analysis showed that there were differences between the two groups of patients, and the AUC value of the prognostic risk model was 0.703, indicating that the model had good accuracy. Multivariate Cox regression analysis revealed that patient age and risk score were independent risk factors for breast cancer. 
Conclusion The immune-related LncRNA prognostic risk model is an independent risk factor for prognosis of breast cancer, which can effectively predict the survival prognosis of breast cancer patients and can be used as an independent prognostic biomarker for breast cancer.

Key words: breast neoplasms, prognosis, immunity