Objective  To investigate the relationship between LncRNA CRNDE and thyroid papillary carcinoma (PTC).

  Methods  T-test, Kruskal-Wallis test, Wilcoxon rank-sum test and Chi-square test were used to evaluate the relationship between clinicopathological characteristics and CRNDE expression. The sensitivity and specificity of CRNDE to PTC were described by area under receiver operating characteristic (ROC) curve (AUC). Kaplan-Meier method and Cox regression analysis were used to evaluate factors that affect prognosis. The correlation between CRNDE and immune cells was described by immunoinfiltration analysis.

  Results  CRNDE expression was increased in PTC, and BRAF V600E mutation was associated with high CRNDE expression in PTC. ROC analysis showed that CRNDE had significant diagnostic ability (AUC=0.839 7). The overall survival (OS) of high CRNDE expression was poor (P=0.012 6), and the expression of CRNDE was independently correlated with the overall survival (OS) of PTC patients (HR=2.131; P=0.001 6). The expression of CRNDE was positively correlated with the infiltration level of B cells, CD8⁺ T cells and macrophages (P < 0.05), and negatively correlated with the infiltration level of CD4⁺ T cells (P < 0.000 1).

  Conclusion  The expression of CRNDE is significantly related to the survival rate and immune infiltration in PTC, and it may be a promising prognostic biomarker in PTC.