Long‐Term Cancer and Mortality After Thymectomy

BACKGROUND: Long-term health effects of thymectomy in adults remain uncertain. Previous reports suggested associations with increased mortality, cancer incidence, and autoimmune disease, although these findings may reflect differences in patient selection, surgical indication, or follow-up duration. We aimed to examine long-term outcomes following adult thymectomy. METHODS: We performed a propensity score-matched retrospective study of patients who underwent thymectomy or comparator cardiothoracic procedures, with follow-up extending to 10 years. Primary outcomes were all-cause mortality, new-onset malignancy, and autoimmune disease. Findings were compared with those reported in a recent study that has raised caution regarding thymic excision. RESULTS: We identified 425 patients who underwent thymectomy and 5401 controls who underwent coronary artery bypass or valve surgery. After matching, 398 patients remained in each group. Thymectomy was not associated with increased mortality at 5 years (HR = 0.63; 95% CI, 0.38-1.04) or 10 years (HR = 0.78; 95% CI, 0.54-1.13). Excluding reclassified thymic cancers, 5-year extrathymic malignancy incidence was 2.3% versus 1.8% (p = 0.54); no significant differences were observed in immune-related disease. Mortality was higher among patients with thymic malignancy. Among MG patients, only one event occurred, precluding reliable estimation. CONCLUSIONS: Thymectomy was not associated with excess mortality or malignancy at 10 years compared with matched cardiothoracic controls. Indication-stratified analyses within the thymectomy cohort showed higher mortality for thymic malignancy, with insufficient events to assess outcomes in MG patients. These findings do not support a generalized survival penalty from thymectomy, though caution is warranted for incidental thymic removal.