Minimally invasive thymectomy (MIT) has demonstrated improved short-term outcomes compared with open thymectomy (OT). Although adoption of MIT for thymoma is increasing, oncologic outcomes have not been well characterized.

This was a retrospective cohort study of adult patients from the National Cancer Database who underwent MIT or OT for Masaoka stage I to II thymoma between 2010 and 2014. The primary outcome was R0 resection. Secondary outcomes included MIT use, perioperative mortality, and length of stay.

Nine hundred forty-three patients from 395 hospitals underwent thymectomy for stage I to II thymoma. MIT was performed in 31.3% (59.7% robotic, 40.3% thoracoscopic). Over the study period MIT utilization increased from 21.0% to 40.2% (trend test, p < 0.001). R0 resection was achieved in 83.1% of MITs (86.6% stage I, 72.7% stage II) and 79% of OTs (85.5% stage I, 65.8% stage II). In multivariable analyses, the likelihood of incomplete resection (R1/2) was associated with stage II tumors (odds ratio, 2.51) and World Health Organization B3 histology (odds ratio, 3.66). R0 resection was not associated with surgical approach (p = 0.17) and did not vary with tumor size (trend test, p = 0.90). Mortality rates at 30 and 90 days were 0% and 0.5%, respectively. MIT was associated with significantly shorter lengths of stay than OT (-1.03 days [95% confidence interval, -1.68 to -0.38]).

The use of MIT for resection of early-stage thymoma is increasing and is not associated with lower rates of R0 resection than OT. Reasons for the relatively low rates of R0 resection among all thymectomies requires further investigation, and long-term outcomes data are needed to better define the oncologic effectiveness of MIT.