Definitions of recurrence and outcome measures were reported as recommended by the International Thymic Malignancies Interest Group [7]. Overall survival (OS) was calculated as the primary outcome from the date of surgery (first pleural surgery, Fig. 1) to the date of death of any cause. Patients without an event were censored at the last time point known to be alive. Disease-free survival was analysed from the date of surgery (first pleural surgery) to the date of recurrence or death from any cause (DFS) [8]. The end-point of interest for cause-specific survival (CSS) was defined as death from TET (censored observations: unrelated deaths and unknown cause of death) [7]. FFR was calculated only in patients after complete surgical resection (R0) from the date of surgery (first pleural surgery) to the date of recurrence and full information on recurrence status [9]. Log-rank tests were employed to compare whole Kaplan–Meier curves. Differences at 1, 3, 5 and 10 years were reported descriptively. Statistical methods are detailed further in the Supplementary Material.