The Reserach Of Thymoma Stereotactic Body Radiation Therapy And Prognosis

Objective:1.We carried out a prospective study of patients with thymoma assigned to receive stereotactic body radiotherapy(SBRT)with PFS as the primary study endpoints.2.We performed a immunohistochemistry analysis to assess the expression of three potential putative predictive biomarkers(Nm23-H1,Ape1,Raf-1)in thymoma samples that could be potentially targetable by prognosis and experimental drugs.Methods:1.A single-institution prospective study was done on thymoma and thymic carcinoma after SBRT between 2005 and 2014.SBRT at a dose of 4000-4500 cGy in 10 fractions was given starting on day 1.The Kaplan-Meier curve and life tables were used to describe survival data.Adverse events were evaluated according to the Common Terminology Criteria for Adverse Events version of the Radiation Therapy Oncology Group(RTOG).2.The expression of biomarkers(Nm23-H1,Ape1,Raf-1)was detected by immunohistochemistry in 120 thymoma tissue samples.For each marker,they defined the percentage of positive tumor cells according to localisation.According to their positive percentage and staining intensity,they were divided into two groups: high expression group and low expression group.The correlation of biomarkers(Nm23-H1,Ape1,Raf-1)expression with clinicopathology and prognosis was performed by SPSS 18.0.Results:1.Thirty-two patients including 39 target lesions were analyses in this study.Almost half of the patients(46.9%)were type C by histopathology and more than half(56.3%)were classified into stage IVA or IVB.The median dose of SBRT for gross tumor volume(GTV)was 56 Gy(range 49-70 Gy).Results showed that the response rate was 96.9% after SBRT and the median tumor shrinkage rate was 62.2%(range 3.8-100%).The local control rate was 81.25%.The radiation-induced side effects were mild,with most grades 1-2 and no grade 3-4.Main adverse reaction was radioactive esophagitis with 8 cases of grade 1 and 3 cases of grade 2.2.In 120 thymoma patients,41 patients(34.2%)had T progression.Single factor analysis showed that in the T patients with Nm23-H1 sensitive mutations,The primary operation patients benefitted more on survival without Nm23-H1(P<0.001).Conclusions:1.Patients treated with SBRT had an excellent local control with mild toxicities,which suggests that SBRT is feasible for the patients with thymic tumors who are unable to undergo either surgery or conventionally fractionated radiation therapy.2.Nm23-H1 was high expression in invasive thymoma.The expression played an important role in the metastasis of thymoma.Based on their expression,Nm23-H1 may be a predictive factor for the poor outcome of thymoma.