There is a small sebaceous gland located behind your breastbone that is often said to be 'useless' in adulthood. But a recent retrospective study suggests that the thymus gland may not be as expendable as experts once thought.

US researchers have found that those who have their thymus removed have an increased risk of death from any cause later in life. They also had an increased risk of developing cancer. The study is purely observational, meaning it cannot show that thymus removal directly causes cancer or other fatal diseases.

But the researchers are concerned about their findings. They argue that until more information is available, preserving the thymus "should be a clinical priority" where possible.

"The magnitude of the risk was something we never expected," oncologist David Scadden told Anne Manning of the Harvard Gazette.

In childhood, the thymus is known to play a critical role in the development of the immune system. When this gland is removed at a young age, patients show long-term reductions in T-cells, a type of white blood cell that fights germs and disease. Children without a thymus also tend to have weaker immune responses to vaccines.

But when a person reaches puberty, the thymus shrinks and produces far fewer T-cells for the body. It can apparently be removed without causing immediate harm and is often removed during cardiothoracic surgery because it is located in front of the heart.

While some patients with thymus cancer or chronic autoimmune diseases such as myasthenia gravis need thymectomy, in which the thymus is surgically removed, this gland is not always an obstacle. It can even be a great help.

Using patient data from a state health system, researchers in Boston compared the outcomes of patients undergoing cardiothoracic surgery: more than 6,000 people whose thymuses were not removed (controls) and 1,146 people whose thymuses were removed.

Even after adjusting for sex, age, race and thymus cancer, myasthenia gravis or post-operative infections, thymectomised patients were almost twice as likely as controls to die within 5 years.

Patients who had their thymuses removed were also twice as likely to develop cancer within 5 years of surgery. Moreover, this cancer was generally more aggressive and often relapsed after treatment compared to the control group.

Why these associations exist is unknown, but researchers suspect that thymus deficiency somehow impairs the healthy function of the adult immune system.

A subset of patients in the study who had undergone thymectomy showed less diverse T-cell receptors in their blood, which could possibly contribute to the development of cancer or autoimmune diseases after surgery.

"Together, these findings support a role for the thymus in adulthood that contributes to new T-cell production and maintenance of adult human health," the study authors conclude.

They say their results strongly suggest that the thymus plays a functionally important role in maintaining our health, right up to the bitter end.

 

Source: https://www.sciencealert.com/