| Objective:To investigate the clinicopathological characteristics of multifocal thyroid micropapillary carcinoma(PTMC)and the risk factors for central lymph node metastasis(CLNM)of PTMC,and to further analyze the relationship between CLNM and the number of cancer foci,total tumor diameter(TTD),tumor distribution and total tumor volume of cN0 multifocal PTMC,so as to provide reference for clinical diagnosis and treatment.Methods:The clinical data of cN0 388 PTMC patients admitted to thyroid Surgery department of The First Hospital of Shanxi Medical University from October 2020 to November 2021and confirmed by pathological examination were retrospectively analyzed.The data were input into statistical analysis software and divided into single-focus PTMC group(230cases)and multi-focus PTMC group(158 cases).The differences of clinicopathological factors between the two groups were compared.The risk factors of lymph node metastasis in central PTMC of cN0 were analyzed by univariate analysis and multivariate Logistic regression.Then according to the number of cancer foci,multi-foci PTMC was subdivided into 2 foci group and≥3 foci group.According to TTD,the multifocal PTMC group was subdivided into TTD≤1cm group and TTD>1cm group.According to the distribution of cancer foci,multifoci were divided into unilateral multifoci group,bilateral multifoci group and bilateral multifoci group.Multiple foci were divided into≤90mm~3 group and>90mm~3 group according to the total volume of tumor.The positive rate of CLNM among different subgroups was compared respectively to clarify the internal correlation between multifoci and CLNM.Results:Among the cN0 388 PTMC patients included in the study,230 patients(59.3%)were single-focus PTMC patients,including 107 patients(27.6%)with tumor volume≤90mm3and 123 patients(31.7%)with tumor volume>90mm3.There were 158(40.8%)patients with multifocal PTMC,including 73(18.8%)patients with multifocal PTMC and TTD≤1cm,and 85(21.9%)patients with multifocal PTMC and TTD>1cm.41 patients(10.6%)had multifocal PTMC with tumor volume≤90mm~3,117 patients(30.2%)had multifocal PTMC with tumor volume>90mm~3.66 cases(17.0%)had multiple foci in unilateral lobule,54 cases(13.9%)had multiple foci in bilateral lobule,and 38 cases(9.80%)had multiple foci in bilateral lobule.Among PTMC patients,126(32.5%)had CLNM,and 262(67.5%)had no CLNM.Statistical analysis of clinicopathological characteristics of single and multiple foci showed that there was no statistical significance in age,gender,nodular goiter and hashimoto’s thyroiditis between patients with multiple foci PTMC and those with single foci PTMC(P>0.05).However,multiple foci showed higher risk of central lymph node metastasis(P<0.001)and capsule invasion(P=0.013<0.05),larger primary tumor diameter(P=0.018<0.05),and larger surgical range(P<0.001).To study the risk factors of lymph node metastasis in central region of PTMC,univariate analysis showed that age,gender,multifocal,primary tumor diameter and external thyroid invasion were correlated with lymph node metastasis in central region(all P<0.05).Further multivariate Logistic regression analysis showed that age<55 years old,male,with external thyroid invasion,and multiple lesions were independent risk factors for central lymph node metastasis in PTMC patients.Further study on the relationship between different multifocal subgroups and CLNM,CLNM with different number of tumors was compared between groups.The results showed that the incidence of CLNM in groups with≥3 cancer foci was the highest and significantly higher than that in other groups(P<0.05).Similarly,the incidence of CLNM in the two-focus group was higher than that in the single-focus group(P<0.001),suggesting that the incidence of CLNM increased with the increase of the number of tumors.Comparison between groups of CLNM with different total tumor diameters showed that the incidence of CLNM was the highest in the multi-focal group with TTD>1cm,which was higher than that in other groups(P<0.05).However,there was no significant difference in CLNM positive rate between single-focus PTMC patients and multi-focus PTMC patients with TTD≤10mm(P=0.071>0.05).Comparison of CLNM with different tumor distribution between groups showed that the risk of CLNM occurrence in bilateral multifocal group was the highest and significantly higher than that in other groups(P<0.05).The risk of CLNM in the unilateral multifocal group was higher than that in the bilateral single-focal group(P<0.05),and the risk of CLNM in the bilateral single-focal group was higher than that in the single-focal group(P<0.05).The results showed that the incidence of CLNM in group 3 with multiple foci and total tumor volume>90 mm~3was the highest and significantly higher than that in other groups(P<0.05).The risk of CLNM occurrence was higher in the group with multiple foci and total tumor diameter≤90mm~3 and the group with single foci and tumor volume>90mm~3than in the group with single foci and tumor volume≤90mm~3(all P<0.05).There was no significant difference in the incidence of CLNM between the group with multiple foci and tumor volume≤90mm~3and the group with single foci and tumor volume>90mm~3(P>0.05).Conclusion:Multifocal PTMC has worse clinicopathological features than single-focal PTMC.Multifoci is an important risk factor for CLNM in PTMC.In patients with multifocal PTMC,the risk of CLNM increased with the increase of the number of tumors.Patients with multi-foci and TTD>1cm PTMC have a higher risk of CLNM than patients with single-foci PTMC and multi-foci and TTD≤1cm.The risk of CLNM is higher in bilateral multifocal distribution than in single focal distribution or other multifocal distribution.Patients with multifocal PTMC with tumor volume>90mm~3 had a higher risk of CLNM than patients with single-focal PTMC and multifocal PTMC with tumor volume≤90mm~3.Therefore,pCLND should be routinely performed in patients with multifocal PTMC with multiple tumors,TTD>1cm,bilateral multifocal tumors,and total tumor volume>90mm~3cN0. |
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