Perioperative outcomes of minimally invasive surgery for large malignant thymic epithelial tumors and for total thymectomy

Purpose Minimally invasive surgery (MIS) for thymic tumors is now accepted widely, in line with improved surgical techniques; however, we occasionally encounter complicated cases of large tumors or of total thymectomy requiring prolonged operative duration or conversion to an open procedure (OP). We reviewed patients registered in a nationwide database to identify the technical feasibility of MIS for thymic epithelial tumors. Methods Data on patients treated surgically between 2017 and 2019 were extracted from the National Clinical Database of Japan. Clinical factors and operative outcomes were calculated by tumor diameter using trend analyses. Perioperative outcomes of MIS for non-invasive thymoma were investigated using propensity score-matched analyses. Results MIS was performed in 46.2% of the patients. The operative duration and conversion rate increased with the tumor diameter ( p < .001). After propensity score-matching, operative duration and postoperative hospital stay were shorter ( p < .001), and the transfusion rate was lower ( p = .007) in patients who underwent MIS than in those who underwent OP for thymomas ≥ 5 cm. Among patients who underwent total thymectomy, blood loss was less ( p < .001) and the postoperative hospital stay was shorter ( p < .001) in those who underwent MIS than in those who underwent OP. There were no significant differences in postoperative complications and mortality. Conclusions MIS is technically feasible even for large non-invasive thymomas or for total thymectomy, although the operative duration and open conversion rate increase with the tumor diameter.