| BackgroundIt is common for papillary thyroid carcinoma(PTC)to be characterized by slow growth and low-level aggressiveness.Many PTC patients are prone to develop lymph node metastasis in the cervical area.According to the related thyroid cancer guideline,patients with unilateral PTC who do not have obvious clinical lymph node metastasis(cN0)on preoperative examination may be treated with thyroid lobectomy(TL).In those patients,the presence of central lymph node metastases(pN1a)may be confirmed by routine pathology after prophylactic central cervical lymph node dissection.According to postoperative thyroid cancer recurrence risk stratification,patients with more than 5 central cervical lymph node metastases,pNla(n≥5),are at intermediate risk of recurrence.Radioactive iodine(RAI)treatment is beneficial for patients to eliminate metastatic lesions,residual cancer tissue,and reduce the possibility of recurrence.Completion thyroidectomy followed by RAI is often advised for PTC patients with pN1a(n≥5).Postoperative complications may occur more frequently after secondary surgery.Long-term outcomes of completion thyroidectomy and RAI therapy for patients are still unclear.Subsequent treatment measures for unilateral PTC patients with pN1a(n≥5)remain controversial.Many controversies currently exist on the necessity of completion thyroidectomy in unilateral PTC patients with pN1a(n≥5).ObjectiveThrough a retrospective cohort study,the effects of both TL and TT on the clinical outcomes of patients with unilateral PTC were adopted.The impact of the number of central lymph node metastases on the recurrence of patients after TL was explored.The extent of surgery for unilateral PTC patients who did not have significant preoperative clinical lymph node metastases could be evaluated.Materials and Methods(Ⅰ)PTC patients with pN1a(n≥5)who underwent surgery from Qilu Hospital of Shandong University and Second Hospital of Shandong University between January 2013 and December 2019 were retrospectively evaluated.Patients with aggressive subtype,tumor maximum diameter>4 cm,gross extrathyroidal extension(gETE),preoperatively positive clinical lymph nodes(cN1),postoperatively pathological lateral cervical lymph node metastasis(pN1b)and distant metastasis were excluded from this analysis.There were 192 patients included in the analysis.Patients were divided into TL and TT groups according to the different surgical methods.Patient data,clinicopathological information,and postoperative data,including recurrence,laryngeal recurrent nerve injury and hypocalcemia were collected.SPSS(25.0,IBM Corporation,Armonk,NY)software was utilized for the statistical analysis,and GraphPad Prism 9 was used for the graphing.The study compared the influence of two surgical methods on recurrence and postoperative complications in patients with PTC.(Ⅱ)PTC patients with pN1a who underwent surgery from Qilu Hospital of Shandong University between January 2015 and December 2019 were retrospectively evaluated.Patients with aggressive subtype,tumor maximum diameter>4 cm,gETE,cN1,pN1b,and distant metastasis were excluded from this analysis.There were 833 patients enrolled in the analysis.Patients were divided into two groups,according to the number of lymph node metastases.Basic patient data and clinicopathological data were collected and matched at a 1:1 ratio using the propensity score matching(PSM)method to correct for variables,e.g.,age,sex,tumor size,multifocality,microscopic capsular invasion and hashimoto thyroiditis between the two groups.The main evaluated outcome was the follow-up data,e.g.,recurrence free survival(RFS).SPSS(25.0,IBM Corporation,Armonk,NY)software was utilized for the statistical analysis,and GraphPad Prism 9 was used for the graphing.The study compared the effects of various numbers of lymph node metastases on the prognosis of patients with unilateral PTC undergoing TL was conducted.Results(Ⅰ)There were 192 patients enrolled in this study(TT group,n=91;TL group,n=101).Five patients with local recurrence were observed during the follow-up.There were 3 patients in the TL group and 2 patients in the TT group developed local recurrence.Except for the tumor maximum diameter,nodular goiter and RAI,there was no significant difference in the baseline clinical data between the two groups after matched analysis.Compared to the TL group,the TT group had a larger tumor maximum diameter(12 mm vs.10 mm,p=0.049),higher proportion of nodular goiter(63.7%vs.22.8%,p<0.001)and higher proportion of RAI treatment(84.6%vs.0%,p<0.001).Local recurrence rates were not statistically different between the TL and TT groups(3.0%vs.2.2%,p=1.000).Kaplan-Meier curves showed no differences in RFS between the TT and TL groups.Subgroup analyses stratified by additional risk factors such as tumor maximum diameter>1 cm,multifocality and microscopic capsular invasion showed no significant difference between the two groups.RAI treatment had no influence on patient recurrence rate(p=0.953).In TT group,the incidence of temporary hypocalcemia was significantly higher than that in TL group(16.5%vs.4.0%,p=0.004).(Ⅱ)There were 833 patients who met the criteria in total involved in the study.A total of 170 patients(85 in each group)were finally analysed after 1:1 PSM.Except for the follow-up time,there was no significant difference in the baseline clinical data between the two groups after matched analysis.A total of 4 patients in all had local recurrence including 3 patients in pN1a(n≥5)group and 1 patient in pN1a(n<5)group.There was no statistically significant difference between two groups(3.5%vs.1.2%,p=1.000).By the end of the study,all patients survived,and none of the 4 patients experienced a second recurrence after the second operation.The difference between the TT and TL groups was not statistically significant in the recurrence analysis(p=0.252).Subgroup analysis including microscopic capsular invasion,tumor maximum diameter>1 cm and multifocality,revealed that there was no difference in RFS between the pN1a(n≥5)and pN1a(n<5)groups according to Kaplan-Meier curves.ConclusionWith regard to PTC patients with pN1a(n≥5),except for the aggressive subtype,tumor maximum diameter>4 cm,gETE,cN1 and distant metastasis,our study revealed no statistically significant differences between thyroid lobectomy and total thyroidectomy.Total thyroidectomy significantly increased the risk of surgical complications,particularly transient postoperative hypocalcemia that which has a negative impact on patients’ long-term quality of life.Patients either in pN1a(n≥5)or pN1a(n<5)group are at similar risk for structural recurrence.This study showed TL plus pCLND maybe an acceptable option for PTC patients with pN1a(n≥5).Frequent active surveillance could be adopted instead of completion thyroidectomy followed by radioiodine therapy in patients with pN1a(n>5). |
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