What is the impact of thymectomy on the health of adults?
Maybe that thymus is busier than we thought! There's a clear association between thymectomy and increased risks for all-cause mortality, cancer, and possibly autoimmune disease. The implications for surgeons are clear: If you can, avoid cutting out the thymus. For primary care clinicians, it is less clear whether these patients would benefit from being monitored more closely than usual.
Thymectomy is often performed as part of cardiothoracic surgery in adults, with the belief that by adulthood the gland has largely involuted and ceased to produce T-cells. These researchers identified 1146 patients who had undergone thymectomy between 1993 and 2020 at Massachusetts General Hospital, and matched them by age, sex, and premorbid conditions with 1146 patients who had undergone cardiothoracic surgery without thymectomy during the same period. Although the groups were balanced by age (56 years), race (86% white), and sex (48% female), they differed with regard to the indication for surgery. Most patients in the control group had coronary artery bypass, valve replacement, or other cardiac procedures as their indication, but 45% of patients in the thymectomy group had cancerous thymic mass and 32% had a noncancerous mass as their indication. All-cause mortality at 5 years was significantly higher in the thymectomy group than in the control group (8.1% vs 2.8%; relative risk [RR] 2.9; 95% CI 1.7 - 4.8). Cancer was also twice as likely in the thymectomy group (7.4% vs 3.7%; RR 2.0; 1.3 - 3.2), with 46% having skin cancer and the rest having a range of solid tumors (including, most commonly, bladder and pancreatic cancers). Recurrence of cancer following treatment was also more common in the thymectomy group (17.1% vs 4.6%; RR 3.7; 1.7 - 8.2). There was no difference in the likelihood of autoimmune disease in the primary analysis, but after excluding patients with pre-operative autoimmune disease, infection, or cancer, the authors saw an increased risk of subsequent autoimmune disease (12.3% vs 7.9%; RR 1.5; 1.02 - 2.0). Given multiple comparisons, however, this should be considered exploratory.
Mark H. Ebell, MD, MS
University of Georgia