Exploring the correlation analysis of immune microenvironment, mutation burden and prognosis of papillary thyroid carcinoma based on Estimate algorithm.Background
 This study aimed to investigate the correlation between immune infiltration and tumor mutational burden (TMB) in papillary thyroid carcinoma.


 Transcriptome sequencing data sets, gene mutation data sets, and clinical data sets were downloaded from The Cancer Genome Atlas (TCGA) database.  The immune and papillary carcinoma stromal scores were calculated using the "Estimate" package of R software.  The relationship between the immune score, stromal score, TMB, and papillary thyroid carcinoma progression-free survival was analyzed.  Pearson's test was used to analyze the correlation between the immune score, stromal score, and TMB.


 Results
 The stromal score and immune score of papillary thyroid carcinoma tissue were lower than those of normal thyroid tissue (P=0.008 and P<0.001, respectively).  There was no significant difference in progression-free survival between the high stromal and low stromal score groups (P=0.075).  The progression-free survival of the high immune score group was better than that of the low immune score group (P=0.029), and the progression-free survival of the low TMB group was better than that of the high TMB group (P<0.001).  The high immune score, low TMB group had the best prognosis (P=0.003).  Univariate Cox analysis showed that age, pathological stage, and TMB were risk factors for progression-free survival [hazard ratio (HR) >1, P<0.05], and that the immune score was a protective factor for progression-free survival (HR <1, P<0.05).  Multivariate Cox analysis showed that age and TMB were independent risk factors for progression-free survival (HR >1, P<0.05), and that the immune score was an independent protective factor for progression-free survival (HR <1, P<0.05).  Correlation analysis showed that the immune and stromal score were both negatively correlated with TMB (r=-0.26, P=0.031 and r=-0.41, P=0.028, respectively).


 The immune and stromal scores of papillary thyroid carcinoma were negatively correlated with TMB.  Thyroid cancer gene mutations inhibit immune cell infiltration and alter the thyroid cancer microenvironment.  The immune score was an independent protective factor for progression-free survival, while TMB was an independent risk factor, both of which can be used for clinical prognosis assessment.  Combined immunological and genomic analysis of papillary thyroid carcinoma can reveal potential prognostic markers and therapeutic targets and provide clues for the tumor immune escape mechanism.
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