Mutation Profiles Of Thyroid Tumors And Its Correlation With Clinicopathological Characteristics And Prognosis

Part oneBackground Follicular thyroid adenoma(FTA),well differentiated tumor of uncertain malignant potential(WDT-UMP)/(follicular tumors with uncertain malignant nature(FT-UMP)and follicular thyroid cancer(FTC)mainly represent the benign,borderline and malignat thyroid follicular lesions.It palys an important role in the patient management if these lesions can be accurately identified by pathologists.In the present study,we aimed to charcterize the mutational profiles of follicular thyroid tumor,to correlated the genetic alterations with clinicopathological features and to identify markers with potential diagnostic and prognostic implications.Materials and methods The present study contains 150 patients diagnosed with follicular thyroid tumors.Targeted sequencing with a panel of 18 thyroid cancer-related genes was performed on 48 tissue samples from follicular thyroid adenoma(FTA),32 follicular tumors of uncertain malignant potential(FT-UMP),17 well-differentiated tumors of uncertain malignant potential(WDT-UMP)and 53 samples from follicular thyroid carcinoma(FTC).The correlation of mutation profiles and clinicopathological features and prognosis were also analyzed.Results Ninty-five nonsilent mutations spanning 14 genes were detected.Mutations were not found in AKT1,ETV6,ALK or NTRK1 genes.Specifically,TERT promoter(TERTp)mutations were exclusively detected in FTC.A total of 80%EIF1AX exon 2 mutations(4/5)and 75%TSHR mutations(3/4)occurred in FTA,whereas the rest of them occurred in FT-UMP.GNAS mutations alone were only detected in FTA and FT-UMP,whereas GNAS mutations along with other gene mutations were detected in FTC.KRAS mutations and TP53 mutations were only presented in borderline or malignant tumors.H/N-RAS mutations were detected in all four subtypes,but were most commonly found in WDT-UMP(p=0.031).All N-RAS mutations were located at codon 61.BRAF V600E and RET fusion were absent in the entire cohort.In FTC cases,EIF1AX mutations were all located at intron 5/exon 6 and correlated with advanced disease(p=0.032).Both EIF1AX and TERTp mutations predicted shorter disease-free survival(p=0.007,p=0.024,respectively).Further analysis revealed that TERTp mutations were correlated with shorter disease-free survival in patients with minimally invasive/encapsulated angioinvasive FTC(p=0.017),but not in those with widely invasive FTC(p=0.297).Conclusions TERTp,EIF1AX,TSHR,GNAS,N/H/K-RAS and TP53 mutations may have diagnostic and prognostic potential in follicular thyroid tumours.Extrathyroidal invasion was the independent predictor of shorter disease-free survival for FTC patients.In clinical practice,TERTp、IFIAX、TSHR、GNAS、N/H/K-RAS、TP53、BRAF gene mutations and RET gene fusion detections were suggested for all the follicular thyroid cancer patients if possible.Part twoBackground Poor differentiated thyroid cancer(PDTC)and anaplastic thyroid cancer(ATC)represent rare but highly lethal thyroid carcinomas and the underlying mechanisms of theses carcinogenesis remain to be fully elucidated.In the present study,we aimed to characterize the mutational profiles of PDTC and ATC in Chinese patients,to observe the correlation between genetic alterations and morphological features and to identify potential markers with potential diagnostic,prognostic and therapeutical significances.Materials and methods Forty-one patients diagnosed with PDTC and 25 diagnosed with ATC were included.Targeted next-generation sequencing with a panel of 18 thyroid cancer-related genes was performed on tissue samples from the 66 patients.Genetic alterations in PDTC and ATC and their correlations with clinicopathological factors including survival outcomes were also analyzed.Results A total of 139 genetic alterations were detected in 32(78%)PDTC and 25(100%)ATC.The most frequently altered genes in the 18 gene panel were BRAF,TP53,TERT and PIK3CA genes.ATC has significantly higher mutation rates of these four genes than PDTC(p=0.005,p=0.007,p=0.005 and p=0.033 respectively).PDTC/ATC with PTC components had more frequent BRAF mutation than pure PDTC/ATC(p=0.008 for PDTC and p=0.003 for ATC,respectively).Ten(77%)ATC with PTC components had BRAF mutations,all of which coexisted with a late mutation event(TP53,TERT or PIK3CA).Nine(22%)oncogenic fusions(6 RET,1 NTRK1,1 ALK and 1 PPARG)were identified in 41 PDTC,whereas only 1(4%)case of NTRK1 fusion was found in 25 ATC).Moreover,all 6 cases of RET fusion were found in PDTC with PTC components,accounting for 33%of PDTC with PTC components.Patients with RET fusion were all female.They were younger(p=0.002),had a smaller tumor size(p=0.017)and better prognosis(p=0.035)than those without RET fusion Based on the univariate Cox regression analysis,predictors of worse overall survival(OS)in PDTC/ATC were age 55 years or more(p=0.001).advanced disease(p=0.004),distant metastasis(p=0.009),BRAF mutations(p=0.008),TP53 mutation(p=0.003),TERT mutation(p<0.001),and PIK3CA mutation(p=0.002).By the multivariate Cox regression analysis,TERT mutation was the independent predictor for OS(p=0.009).Moreover,concurrent mutations in TERT and another gene(BRAF or PIk3CA)had a synergistic effect on OS in PDTC/ATC patients.Concurrent TERT and PIK3CA mutations were associated with poor OS after adjustment for tumor,node and metastasis stage in PDTC/ATC patients(p=0.001).Conclusion ATC has a higher mutation rate than PDTC,whereas PDTC has a higher rate of oncogenic fusion.ATC with PTC component is typically characterized by BRAF mutation with a late mutation event,whereas PDTC with PTC component is more closely correlated with RET fusion.These results indicate ATC and PDTC might have a different therapeutic strategy based on the differential molecular profiles.RET fusion may predict a better prognosis in PDTC/ATC.TERT and concurrent PIK3CA mutation predict worse OS in PDTC/ATC.