Oncologic outcomes and predictors of recurrence following minimally invasive and open surgery for thymoma.

Background: Thymomas are rare neoplasms of the mediastinum with an incidence of 0.15 per 100,000 person-years but represent the most common tumor of the anterior mediastinum in adults. Complete surgical removal is the mainstay treatment for thymomas. While minimally invasive surgeries (MIS) for thymoma are increasing, it remains unknown if MIS is oncologically equivalent to traditional open surgical techniques (OTs). The aim of the present study was to characterize outcomes and identify risk factors associated with recurrent disease in patients undergoing surgery for early-stage thymoma, with specific attention to the influence of surgical approach. Methods: We conducted a retrospective cohort study using a database of thymic epithelial tumor patients evaluated at Indiana University Melvin and Bren Simon Comprehensive Cancer Center from 2005 to 2021. A total of 178 stage I-III thymoma patients who underwent surgery [OT: n=129 (72%), MIS: n=49 (28%)] were identified and reviewed to determine factors predictive of outcomes. Results: The median age was 56.2 years and 56% were female. The median follow-up was 64 months. The stage distribution was I 39%, II 44%, and III 16%. Complete resection was achieved in 82% of patients. Multivariable analysis demonstrated that presurgical sampling through image-guided fine needle aspiration (FNA)/core [hazard ratio (HR) =2.738] and thoracoscopic biopsies (HR =2.646), MIS approach (HR =2.481), greater stage (HR =2.951), and incomplete resection (HR =2.569) were associated with inferior disease-free survival (DFS). However, no significant difference was observed in DFS or overall survival (OS) on Kaplan-Meier analysis stratified by surgical approach. Of the 14 patients who developed pleural recurrence after undergoing unilateral MIS, all pleural metastases were ipsilateral to the surgical approach. Conclusions: Our data demonstrates that both OT and MIS have excellent outcomes with respect to OS for early-stage thymoma. For low surgical risk patients with small anterior mediastinal masses which are suspicious for thymoma, removal using an MIS approach without biopsy appears reasonable. In higher-stage tumors, an MIS approach should be utilized cautiously at centers with surgical expertise.