Comparison of Oncologic Outcomes After Partial and Total Thymectomy for Stage I Thymomas

Total thymectomy (TT) has been the standard treatment for thymoma. However, many thymomas may be amenable to partial thymectomy (PT), which can achieve similar R0 resection frequency with favorable perioperative outcomes. We sought to determine whether PT results in oncologic outcomes similar to TT for noninvasive thymomas.

We queried the International Thymic Malignancy Interest Group retrospective database from 2000 to 2014 for patients with stage I thymomas without myasthenia gravis undergoing TT or PT. Outcomes were freedom from recurrence (weighted for age and T category 1a vs 1b) and overall survival, with inverse probability weights of patient factors as predictors of TT.

Included were 692 patients, with 158 PT (23%) and 534 TT (77%). PT patients were younger with better performance status. R0 resection and histology were similar. The PT group had more T1b thymomas. Adjuvant chemotherapy and radiotherapy were more frequent after PT. There was no difference in new-onset myasthenia gravis. Weighted freedom from recurrence (hazard ratio, 1.09; P = .81) and overall survival (hazard ratio, 0.62; P = .11) was similar for PT compared with TT.

PT for stage I thymomas without myasthenia resulted in statistically similar recurrence and survival, and no difference in the development of new-onset myasthenia gravis, compared with TT. These results add to a growing body of literature around PT, suggesting it may be considered for stage I thymomas when R0 resection can reasonably be achieved. Surgeons performing PT are encouraged to report their outcomes to continue this discussion.