| Thymoma is a relatively slow-growing mediastinal neoplasms arising from the epithelial cells of the thymus gland.During the course of the disease,thymoma is usually associated with paraneoplastic disorders,mainly myasthenia gravis(MG).The impact of MG on prognosis of thymoma patients has been controversial in the academic community.Therefore,the clinical data of 203 patients underwent surgical procedure related to thymoma with MG in the Eighth Medical Center of the Chinese People’s Liberation Army General Hospital and Cancer Hospital Chinese Academy of Medical Sciences from September 2002 to March 2018 were enrolled as the baseline group(MG group).A total of 7 clinical factors including gender,age,WHO pathological classification,Masaoka stage,resection status,postoperative adjuvant radiotherapy and chemotherapy were used as matching criteria.By using the propensity score matching(PSM)method(1:1),203 cases were selected as the control group(non-MG group)from 1073 patients with simple thymoma receiving thymectomy during the same period.After a balanced sample of covariance was obtained,the survival rate was calculated by Kaplan-Meier method,and comparisons between survival curves were performed by log-rank test.This study aims to evaluate the impact of MG on prognosis of patients with thymoma after operation.In addition,thymoma with MG as a rare clinical disease has unique clinicopathological characteristics and prognostic factors.Therefore,this study further analyzed the clinical and pathological characteristics of 203patients with thymoma combined with MG after operation in the MG group.The survival rate was calculated by Kaplan-Meier method.Log-rank test was used for univariate analysis.Cox proportional risk regression model was used for multivariate prognostic analysis.The aim of the present study was to summarize the clinicopathological features of patients with thymoma combined with MG and to explore the relevant factors affecting the prognosis of postoperative thymoma patients combined with MG.The study results showed that a total of 203 pairs of patients were successfully matched in both groups by using PSM method.There was no significantly difference in clinical baseline data between the MG group(n=203)and non-MG group(n=203)(All,P>0.05).The 5-year overall survival rates for MG group and non-MG group patients was 93.0%and93.8%respectively.The 10-year overall survival rates for MG group and non-MG group patients was 80.6%and 88.4%respectively.There was no significantly difference in overall survival between the two matched groups(P=0.556).A total of 203 thymoma patients with MG were collected retrospectively in this study,including 117 males and 86 females.The median age at the time of thymoma combined with MG diagnosis was 47years(range,18～76 years).According to the Osserman classification of MG:I type:72 cases(35.5%),IIA type:21 cases(10.3%),IIB type 89cases(43.8%),III type:13 cases(6.4%),IV type:8 cases(4.0%),and V type:0 cases(0%).The thymomas was classified according to WHO histological classification:A type:13 cases(6.4%),AB type:25 cases(12.3%),B1 type:30 cases(14.8%),B2 type:87 cases(42.9%),B3 type48 cases(23.6%)and C type:0 case(0%).The Masaoka’s clinical stage of the thymomas was as follows:I stage:105 cases(51.7%),II stage:59cases(29.1%),III stage:24 cases(11.8%),IVa stage:15 cases(7.4%)and IVb stage:0 case(0%).All patients underwent surgical treatment,including 186 cases of R0 resection,10 cases of R1 resection and 7 cases of R2 resection.Postoperative radiotherapy,chemotherapy and chemoradiotherapy were performed on 81,9 and 12 patients respectively and 101 patients were untreated.203 patients were followed up for 2 to 228 months,and median follow-up time was 91 months.The 3-and 5-year overall survival rates for 203 patients with thymoma combined with MG after operation were96.9%and 93.0%respectively.The 5-year survival rates for WHO A to B1 and B2 to B3 patients was 96.8%and 91.0%respectively.The 5-year survival rates for Masaoka I to II and III to IVa patients was 96.5%and78.1%respectively.The 5-year survival rates for R0 resection and R1/R2resection patients was 95.7%and 58.2%respectively.The 5-year survival rates for thymoma patients without or with postoperative adjuvant radiotherapy was 96.1%and 89.3%respectively.The 5-year survival rates for thymoma patients without or with postoperative adjuvant chemotherapy was 94.5%and 74.2%respectively.Univariate analysis showed that WHO pathological classification(χ~2=6.000,P=0.014),Masaoka stage(χ~2=27.122,P<0.001),resection status(χ~2=39.456,P<0.001)and postoperative adjuvant chemotherapy(χ~2=18.116,P<0.001)may be associated with survival in thymoma patients combined with MG after operation.Cox multivariate analysis showed that resection status(HR=0.325,95%CI:0.113～0.935,P=0.037)was an independent prognostic factor in the thymoma patients combined with MG after operation.From the above results,the following conclusions could be drawn,for operable thymoma patients,MG was not associated with overall survival in patients with thymoma.The pathological subtype of patients with thymoma combined with MG were mainly type B2,type IIB was the most common Osserman type.Masaoka stage was mainly early stage I and II,and the main postoperative comprehensive treatment modality was alone radiotherapy.Resection status was an independent prognostic factor in the thymoma patients combined with MG after operation. |
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