An American study has found that the thymus gland, which is located behind the sternum and is often said to be “useless,” may fight cancer. The study was published in the New England Journal of Medicine, and was written about on the Science Alert website.
The researchers found that those who remove the thymus face an increased risk of death from any cause later in life, and also face an increased risk of cancer.
“We discovered that the thymus gland is absolutely essential to health,” David Scadden, an oncologist at Harvard University, said when the research was published. “If it wasn’t there, people’s risk of death and their risk of cancer would be at least double.”
The study is based on observation only, which means it cannot directly prove that removing the thymus gland causes cancer or other fatal diseases.
But the researchers are concerned about their findings. Until we know more, they claim that thymus preservation “should be a clinical priority” where possible.
It is known that the thymus gland plays a crucial role in the development of the immune system in childhood. When the gland is removed at an early age, patients show a long-term decline in T cells, a type of white blood cell that fights germs and disease.
Moreover, children who do not have a thymus gland also tend to have a weak immune response to vaccines.
But by the time a person reaches puberty, the thymus gland shrinks and produces far fewer T cells for the body. They appear to be able to be removed without immediate harm, and because they are located in front of the heart, they are often removed during heart surgery.
Thymus cancer
But while some patients with thymic cancer or chronic autoimmune diseases, such as myasthenia gravis, require a thymectomy, which is surgically removed.
Using patient data from the government health care system, researchers in Boston compared outcomes for patients who underwent cardiothoracic surgery: more than 6,000 people (controls) who did not have their thymus removed and 1,146 people who had their thymus removed.
Those who underwent thymectomy were almost twice as likely as controls to die within 5 years, even after adjusting for sex, age, race, and those with thymic cancer, myasthenia gravis, or infection after surgery.
Patients who had their thymus removed were also twice as likely to develop cancer within 5 years of surgery.
Moreover, this cancer was generally more aggressive and often recurred after treatment compared to the control group.
“This suggests that the consequences of removing the thymus should be carefully considered when considering thymectomy,” Scadden said.
No one knows why these associations exist, but researchers suspect that thymus deficiency somehow messes with the healthy function of the immune system in adults.
A group of patients in the study who underwent thymectomy showed fewer various T-cell receptors in their blood tests, which may contribute to the development of cancer or autoimmune diseases after surgery.
“Taken together, these findings support a role for the thymus gland in producing new T cells in adulthood and maintaining adult health,” the study authors conclude.
Their results, they say, strongly suggest that the thymus gland plays an important functional role in our health.