Minimally Invasive versus Open Thymectomy for Thymic Malignancies: Systematic Review and Meta-Analysis

Complete resection is the standard of care for treatment of thymic malignancies. The use of minimally invasive surgery remains controversial. We searched online databases and identified studies from 1995 to 2014 that compared minimally invasive to open thymectomy for thymic malignancies. Study end points included operative blood loss, operative time, respiratory complications, cardiac complications, length of hospital stay, R0 resection, and recurrence. We summarized outcomes across studies using random-effects meta-analysis to account for study heterogeneity. We calculated ORs for binary outcomes and standardized mean differences for continuous outcomes. We calculated incidence rate ratios for the number of recurrences, accounting for total person-time observed in each study. Of 516 potential reference studies, 30 with a total of 2038 patients met the inclusion criteria. Patients with Masaoka stage I or II thymic malignancy constituted 94.89% of those in the minimally invasive surgery (MIS) group and 78.62% of those in open thymectomy (open) group. Mean tumor size was 4.09 cm (MIS) versus 4.80 (open). Of the 1355 MIS cases, 32 were converted to open cases. Patients in the MIS group had significantly less blood loss; however, no significant differences in operating time, respiratory complications, cardiac complications, or overall complications were identified. Length of stay was shorter for patients in the MIS group. When patients with Masaoka stage I and II thymic malignancy only were analyzed, there was no difference in rate of R0 resection or overall recurrence rate. One postoperative death occurred in the open group. The results of this unadjusted meta-analysis of published reports comparing minimally invasive with open thymectomy suggest that in selected patients with thymic malignancy, minimally invasive thymectomy is safe and can achieve oncologic outcomes similar to those of open thymectomy.