The Survival Impact of Adding Postoperative Radiation Therapy (PORT) to Adjuvant Therapies in Locally Advanced Resected Thymic Carcinoma (TC): A Meta-Analysis

Abstract

TC is a rare malignancy with often poor prognosis. Surgery remains the primary curative therapeutic approach with chemotherapy and/or PORT used as adjuvant modalities in an attempt to improve patients’ outcomes. Published comparative studies have reported conflicting results for PORT. The benefit of additional PORT in Masaoka-Koga stages II&III TC remains controversial. The purpose of this meta-analysis is to evaluate the impact of additional PORT to surgery with or without chemotherapy on overall survival (OS) in patients with resected Masaoka-Koga stages II&III TC. A review of the medical literature was conducted using online databases. Inclusion criteria consisted of (i) resected Masaoka-Koga stages II&III TC (ii) English language (iii) studies reporting OS with hazard ratios (HR) or Kaplan-Meier curves, and (iv) OS data on patients that underwent PORT versus those that did not. Studies that combined stages II&III with other stages were allowed as long as the preponderance of the sample consisted mainly of stages II&III. Those that did not separate Thymoma and Thymic carcinoma were excluded. A meta-analysis was conducted using an inverse variance method with random-effects model. Eight retrospective series with a total of 4,321 patients were included and analyzed. Two studies reported data on stages II&III and one study reported on stages III&IV. Two studies reported data that included stages I through III and three studies reported data that included stages I through IV. The addition of PORT was found to significantly impact OS in patients with resected stage II&III TC (HR 0.78, 95%CI:0.68-0.88). This is the first meta-analysis to show that the addition of PORT to adjuvant therapies is associated with survival benefit in a cohort of resected TC with preponderance of Masaoka-Koga stages II&III.