Sometimes removed during heart surgery, the small butterfly organ known as the thymus might be more critical for human health than once thought.
The thymus is a gland located behind the breastbone that primarily produces and matures immune cells called T cells — mostly during early childhood. However, as a child becomes an adolescent, the thymus shrinks and slows immune cell-related activities. So, many experts consider the thymus an essentially useless organ.
Surgeons sometimes remove the gland during heart surgery to make it easier to access the heart. Doctors also remove the thymus in some people with myasthenia gravis, a condition associated with the gland, and in people with thymus tumors.
However, new research suggests that thymus removal may have grave consequences in the long term, as it may increase the risk of death from all causes.
The study, published on August 3 in The New England Journal of Medicine, compared the risk of cancer, autoimmune disease, and death among people who underwent thymectomies during cardiothoracic surgery to matched controls who had similar surgery but did not have their thymus removed.
After a more than five-year follow-up, the scientists discovered that all-cause mortality and deaths from cancer were higher among people with their thymus removed than among the general population.
The team also measured T-cell production and plasma cytokine levels in 22 people with thymectomies and 19 with their thymus intact. They found that people who had undergone thymectomy had less production of new CD4+ and CD8+ lymphocytes and higher levels of pro-inflammatory cytokines in the blood.
The scientists suggest that the thymus may be an essential organ long past adolescence. And removing it may increase the risk of death from various causes, including cancer. Moreover, not having a thymus may increase the chances of autoimmune disease.
Study authors hope these findings will lead to a review of clinical guidelines for thymus removal. In addition, the team plans to conduct future investigations to examine whether the thymus plays a role in healthy aging.
- The New England Journal of Medicine. Health Consequences of Thymus Removal in Adults.
- Science. Doctors have long considered the thymus expendable. But could removing it be fatal?