The New England Journal of MedicineHealth Consequences of Thymus Removal in Adults

Thymectomy in Adults Linked to Increased Mortality and Cancer Risk, Study Finds

A recent study has shed new light on the potential consequences of thymectomy in adults, suggesting that the removal of the thymus may have significant implications for immune competence and overall health. The research indicates a higher risk of mortality and cancer among patients who underwent thymectomy compared to controls, with potential implications for surgical practices and patient care.

Study Design:

• The study evaluated the risk of death, cancer, and autoimmune disease among adult patients who had undergone thymectomy compared with demographically matched controls who had undergone similar cardiothoracic surgery without thymectomy.
• T-cell production and plasma cytokine levels were also compared in a subgroup of patients.
• After exclusions, 1,420 patients who had undergone thymectomy and 6,021 controls were included in the study; 1,146 of the patients who had undergone thymectomy had a matched control and were included in the primary cohort.

Key Findings:

• At 5 years after surgery, all-cause mortality was higher in the thymectomy group than in the control group (8.1% vs. 2.8%; relative risk, 2.9; 95% confidence interval [CI], 1.7 to 4.8), as was the risk of cancer (7.4% vs. 3.7%; relative risk, 2.0; 95% CI, 1.3 to 3.2).
• The risk of autoimmune disease did not differ substantially between the groups in the overall primary cohort, but a difference was found when patients with preoperative infection, cancer, or autoimmune disease were excluded from the analysis (12.3% vs. 7.9%; relative risk, 1.5; 95% CI, 1.02 to 2.2).
• In the subgroup of patients in whom T-cell production and plasma cytokine levels were measured, those who had undergone thymectomy had less new production of CD4+ and CD8+ lymphocytes than controls and higher levels of proinflammatory cytokines in the blood.

Conclusion:

• The study concludes that all-cause mortality and the risk of cancer were higher among patients who had undergone thymectomy than among controls. Thymectomy also appeared to be associated with an increased risk of autoimmune disease when patients with preoperative infection, cancer, or autoimmune disease were excluded from the analysis.

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Did You Know?
The thymus is most active during infancy and childhood. It gradually shrinks after puberty and is replaced by fatty tissue, a process known as thymic involution. Despite its reduced size and activity in adults, the thymus continues to play a role in immune function throughout life.