2023-08-20 18:15:00
(or T cells) before birth and during childhood, is often thought to be a non-functional organ in adults, and is sometimes removed during cardiac surgeries to facilitate access to the heart and major blood vessels.
A study published in August 2023 in the New England Journal of Medicine shows that it is in fact essential for the health of adults in general and for the prevention of cancer and possibly autoimmune diseases.
David T. Scadden of Massachusetts General Hospital (Harvard University) and colleagues assessed the risk of death, cancer and autoimmune diseases in 1,146 adults who had their thymus removed during surgery and in 1 146 demographically matched participants who underwent similar surgery without thymectomy. They also measured T cell production and blood levels of immunity-related molecules in a subset of the participants.
Results :
Five years following the operation, 8.1% of patients who underwent thymectomy died, compared to 2.8% of those who did not undergo thymus removal, a 2.9 times higher risk of death.
During the same period, 7.4% of patients in the thymectomy group developed cancer, compared to 3.7% of patients in the control group, a 2.0 times higher risk.
Although the risk of autoimmune disease did not differ significantly between the thymectomy group and the control group as a whole, a difference was observed when patients who had an infection, cancer or autoimmune disease before surgery were excluded from the analysis.
After excluding these people, 12.3% of patients in the thymectomy group developed an autoimmune disease, compared to 7.9% in the control group, i.e. a risk 1.5 times higher.
In the subgroup of patients in whom the production of T cells and immunity-related molecules was measured (22 in the thymectomy group and 19 in the control group, with an average follow-up of 14.2 years postoperatively), those who had thymectomy had consistently lower production of new CD4+ and CD8+ T cells than controls and higher levels of pro-inflammatory cytokines in the blood.
“We discovered that the thymus is absolutely necessary for health. If it is not there, the risk of death and cancer is at least doubled”, summarizes David T. Scadden, principal author.
Psychomedia with sources: Massachusetts General Hospital, New England Journal of Medicine (NEJM), NEJM.
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