Retrospective Analysis Of Adjuvant Radiotherapy In Invasive Thymoma

objective:The data of99patients with invasive thymoma were retrospectively analyzed to explore the therapeutic value of the adjuvant radiotherapy in patients with invasive thymoma who underwent complete resection.Methods:A total of99patients with invasive thymoma underwent radical operation between January2002and October2012in our hospital, among them,38patients were combined with radiotherapy. The median radiation dose was56Gy (32-66Gy). Sixty-six patients were treated with conventional radiotherapy, and22patients with conformal or intensity-modulated radiotherapy. The Kaplan-Meier method and Cox proportional hazard regression model were utilized to compute the survival and prognosis factors analysis.Results:Disease-free survival rates were91.7%and85.7%, overall survival rates were92.7%and86.9%, and Disease-specific survival rates were94.2%and86.7%, for all99patients at5and10years, respectively. Disease-free survival rates at5and10years were84.2%and74.2%, respectively, for the adjuvant radiation group, and96.7%and96.7%, respectively, for the group that underwent surgery alone (P=0.024). Disease-specific survival rates at5and10years were90.2%and82.7%, respectively, for the adjuvant radiotherapy group, and96.2%and96.2%, respectively, for the group that underwent surgery alone (P=0.277), the statistical results mentioned above demonstrated that the adjuvant radiation did not significantly reduce recurrence rates or improve survival rates. The disease-free survival rates and disease-specific survival rates were not significantly improved in the adjuvant radiation and surgery alone group whether in the Masaoka staging (Ⅱ、Ⅲ、Ⅳ), WHO classification (A+AB+B1、B2、B3), or pleura invasion staging (P0、P1、 P2) comparison. In the subgroup analysis of the radiotherapy, disease-free survival rates at5and10years were100%and83.3%, respectively, for the group(doze<50Gy), and74.8%and68.0%, respectively, for the group (doze>50Gy)(P=0.166), and disease-free survival rates at5and10years in the group (doze<50Gy) were both higher than the group (doze>50Gy). Disease-free survival rates at5and10years were95.2%and95.2%, respectively, for the conformal or intensity-modulated group, and74.9%and58.2%, respectively, for the conventional group (P=0.061), and disease-free survival rates at5and10years in the conformal or intensity-modulated group were both higher than the conventional group. On multivariate analysis, the odd ratio (OR) of age less than30years and WHO classification associated with disease-free survival rates were0.096(P=0.039) and2.03(P=0.043), respectively.Conclusions:In this study, for the patients with invasive thymoma who underwent complete resection, their conditions were not significantly improved after postoperative radiation. The radiotherapy was not correlated with Masaoka staging, WHO classification and pleura invasion staging. Age less than30years and WHO classification were two significant independent prognostic factors which influence disease-free survival in the completely resected invasive thymoma.37figures,11tables,30references.