Mortality Risk and Cause of Death Associated With Removal of the Adult Thymus: Analysis of the U.S. Thymoma Population.

INTRODUCTION

Recent studies have suggested a continued role of the adult thymus in the immune system and an increase in 5-year mortality and cancer incidence related to its removal. We sought to corroborate these findings in patients undergoing thymectomy for thymoma in the United States.

METHODS

The National Cancer Database (NCDB) and the Surveillance Epidemiology and End Results (SEER) database from 2004 to 2022 were used to identify patients who underwent a total or partial thymectomy for localized (SEER) or small (NCDB) thymoma. Five-year survival and cause of death were compared with (1) the demographically adjusted U.S. population and (2) propensity-matched patients who had undergone surgery for favorable-prognosis breast or thyroid neoplasms.

RESULTS

The 5-year survival of 1186 patients (SEER) and 1307 patients (NCDB) who underwent total thymectomy for localized or small thymoma was not significantly different from the demographic-adjusted U.S. population or propensity-matched patients who had undergone thyroid lobectomy for thyroid cancer or partial mastectomy for ductal carcinoma in situ (DCIS) in both NCDB and SEER (93% versus 93%; 93% and 92% versus 93% and 92%; 95% and 94% versus 95% and 94%). There was no significant difference in survival between partial and total thymectomy (p = 0.16 SEER; p = 0.78 NCDB). Death from secondary cancer was rare after thymectomy (4.2 deaths/1000 person-years) and was not significantly different from that in the patients with resected breast or thyroid cancer.

CONCLUSIONS

Thymectomy in adults with small or localized thymomas was not associated with increased 5-year mortality or cancer death. Longer-term outcomes and specific immunologic end points deserve further study.