Margin-negative resection and long-term survival following robot-assisted thymectomy for thymoma: A tumor size stratified analysis

Objective: Although open thymectomy has traditionally been the gold standard for resection of large thymic tumors, growing evidence has suggested minimally invasive thymectomy to confer comparable survival. However, the influence of incremental increases in tumor size on margin-negative resection and long-term survival following minimally invasive thymectomy remains understudied. Methods: All patients aged 18 years and older who underwent thymectomy for Stage I through III thymoma were tabulated from the 2010-2022 National Cancer Database. Those undergoing thoracoscopic or robotic procedures comprised the video-assisted thoracic surgery (VATS) and robot-assisted thoracic surgery (RATS) cohorts, respectively (others: open thymectomy). Tumor size was stratified as ≤4 cm, 4 to 6 cm, 6 to 8 cm, and >8 cm. Results: Of 5132 patients, 2562 (50%) underwent open thymectomy, 692 (13%) VATS, and 1878 (37%) RATS. Overall, 48% of neoplasms ≤4 cm were performed using RATS, compared with 41% of 4 to 6 cm, 34% of 6 to 8 cm, and 18% of >8 cm in size. Following doubly robust risk-adjustment, RATS remained associated with significantly higher odds of achieving R0 for tumors ≤4 cm (adjusted odds ratio [AOR], 1.78; 95% CI, 1.03-3.10), and equivalent likelihood for neoplasms 4 to 6 cm (AOR, 1.01; 95% CI, 0.63-1.60), 6 to 8 cm (AOR, 1.55; 95% CI, 0.87-2.76), and >8 cm (AOR, 0.73; 95% CI, 0.40-1.47; Reference category: open thymectomy). Among tumors ≤8 cm, VATS was linked with similar R0 odds as open thymectomy. Comparable survival was observed at 5 and 10 years across operative approaches and size strata. Conclusions: Utilization of RATS has rapidly increased since 2010. Relative to open thymectomy, RATS was associated with at least noninferior likelihood of achieving R0 for lesions ≤4 cm, and equivalent odds for tumors >4 cm, as well as comparable survival. Our findings underscore the safety and efficacy of minimally invasive thymectomy for appropriately selected larger thymomas.