ROBOT-ASSISTED THYMECTOMY FOR LARGE THYMOMAS: SURGICAL AND LONG-TERM ONCOLOGICAL OUTCOMES FROM A MULTICENTER STUDY

OBJECTIVES This study aimed to evaluate surgical and oncological outcomes of Robot-assisted (RATS) thymectomy in the treatment of large (diameter >5 cm) thymomas. METHODS Clinical data of 318 thymectomies for thymoma [117 (36.8%) for concomitant Myasthenia Gravis (MG)], performed in 7 high volume centers from 2010 to 2023, were retrospectively reviewed. Surgical outcomes were evaluated: 1.in the RATS group per thymoma size (<5 vs >5 cm); 2.in large thymomas per surgical approach (RATS vs open/RATS vs VATS). KaplanMeier and Cox-regression analyses were used to identify prognostic factors for oncological outcomes. To reduce any selection bias, a 1:1 propensity score match (PSM) analysis was performed for large thymomas. RESULTS 132 RATS thymectomies were performed: 59 (44.7%) for small [MG: 34 (57.6%)] and 73 (55.3%) for large [MG: 22 (30.1%)] thymomas. Conversion (p=0.48), significant complications (p=0.26) and hospital stay (p=0.79) were similar in both groups. Overall, 208 large thymomas were operated on: 73 (35.1%) RATS [MG: 22 (30.1%)], 118 (56.7%) open [MG: 38 (32.2%)] and 17 (8.2%) VATS (MG: 0%). More post-operative complications (p<0.001) but similar major complications (p=0.11) and a longer in-hospital stay (p<0.001) were recorded in an open group compared to RATS for large thymomas without differences in the MG population (p=0.77). While comparing RATS to the VATS group (with a significant difference in MG between groups, p<0.001), no difference was recorded in conversion (p=0.52), complications (p=0.75) and hospitalization (p=0.08). Five-year OS (95% vs 85%, p=0.14) and DFS (86% vs 93%, p=0.18) of large thymomas were comparable between RATS and the open group. Prognostic factors for oncological outcomes for large thymomas were confirmed after PSM. Adjuvant radiotherapy was the only prognostic factor (HR=6.11, 95%CI:1.27-29.40, p=0.02) affecting DFI, while no factor was confirmed for OS at multivariable analysis. CONCLUSIONS RATS is a safe and effective approach for treating large thymomas.