Impact of postoperative surveillance via computed tomography after radical resection for thymoma.

Background: Outpatient follow-up using computed tomography (CT) after thymoma resection is recommended to evaluate tumor recurrence and detect second malignancies. However, the optimal interval for CT surveillance remains unclear. We aimed to investigate the association between CT surveillance intervals and postoperative survival after thymoma resection. Methods: This retrospective study analyzed 143 patients who underwent periodic CT scans after complete thymoma resection at a single institution between 2006 and 2022. Patients were stratified into three groups based on CT interval: half-, 1-, and 2-year groups. CT intervals were stratified according to the attending physician's clinical judgment. Overall survival (OS), recurrence-free survival (RFS), tumor recurrence rates, and post-recurrence treatments were compared among the three interval groups. A multivariate analysis was performed to evaluate the independent prognostic impact of CT intervals. Results: Among the 143 patients included, 82 were assigned to the half-year group, 33 to the 1-year group, and 28 to the 2-year group. The 7-year OS rates were 96.1% in the half-year group, 100% in the 1-year group, and 100% in the 2-year group (P=0.34). The 7-year RFS rates were 85.2%, 92.3%, and 88.1% in the half-, 1-, and 2-year groups, respectively (P=0.37). No significant differences were found in overall and RFS among the three groups. Tumor recurrence rates were 11.0% in the half-year group, 3.0% in the 1-year group, and 7.1% in the 2-year group (P=0.38). No significant differences were noted in recurrence detection modalities and treatment approaches among the three groups (P>0.99, 0.99). In the multivariate analysis, CT follow-up interval was not significantly associated with OS. Conclusions: Postoperative CT follow-up at intervals longer than 1 year may be acceptable and feasible for patients after thymoma resection.