The larger and more functional the thymus remains in an adult, the lower the risk of disease. This is shown by a large current US study. The condition of the thymus gland can also influence the success of immunotherapy against cancer Researchers report in the journal “Nature”..

The thymus gland behind our breastbone is an important training center for immune defense in newborns and children. T cells mature in this organ and learn to distinguish the body’s own cells and tissue from invading pathogens or pathological changes. Natural killer cells are also produced in the thymus, as researchers only discovered in 2025.

In adults However, the thymus was long considered unnecessary. This is because the immune organ shrinks with age and converts the tissue it needs to function into fatty tissue. But in 2023, a study showed that people who had their thymus removed had a significantly higher risk of cancer and early death.

Not everyone’s thymus breaks down at the same rate

It is now clear that there are individual differences in the condition of the thymus gland: not every adult has this organ degenerated to the same extent – and this has a measurable effect on health. Simon Bernatz from Harvard Medical School in Boston and his colleagues discovered this when they evaluated data from a total of 27,500 participants in two long-term US studies that ran for more than twelve years.

For their analyses, the researchers first determined the size, shape and nature of the thymus in the test subjects using computer tomography. From this they created an index of thymus health. This showed: How quickly the thymus gland is broken down varies from person to person. Your condition therefore depends on your age, but also on lifestyle factors such as obesity or smoking. In women, the thymus also degenerates more slowly on average than in men.

Less cancer and cardiovascular disease with a healthy thymus

But how do these differences affect health? Bernatz and his team investigated this by comparing the thymus index with the participants’ health data over more than twelve years. Specifically, they determined whether there is a connection between thymus health and the risk of lung cancer and other types of cancer, cardiovascular disease and related death.

In fact, there was a connection: people with good thymus health had a 63 percent lower risk of cardiovascular disease and a 35 percent reduced risk of lung cancer. Mortality from these and other diseases was also lower. If the thymus condition was good, it was 13.4 percent, but if it was bad, it was 25.5 percent. “These relationships were consistent across all analyzes and remained even when age and possible other influencing factors were taken into account,” reports the team.

Also influences cancer immunotherapy

The condition of the thymus could even the effectiveness of cancer treatments influence. This is suggested by a second study with almost 3,500 cancer patients, including 1,200 lung cancer patients. In this, Bernatz and his team investigated whether there is a connection between thymus health and the effect of immunotherapy with checkpoint inhibitors.

The result: Immunotherapy worked better in cancer patients with good thymus health. They had a 37 percent lower risk of further tumor growth progression and a 44 percent lower risk of dying from the cancer, as the researchers report. This was particularly evident in certain types of lung cancer and melanoma. In some cases, the CT scans of the thymus could be used to predict how successful the immunotherapy was.

“These results identify thymus health as a previously unrecognized factor influencing immunotherapy,” state Bernatz and his team. Analyzes of T cells and immune signaling pathways provided them with a possible reason for this connection. These showed that the T cells of patients with good thymus health had a greater variety of receptors on their surface and certain signaling pathways were more active.

Can we influence our thymus health?

The thymus is more important to our health than long thought – even in adults. Because he Doesn’t seem to be functional at all even in old age. Instead, it still influences the function of our immune system. “The thymus could explain why some people are more susceptible to certain diseases, why this increases with age and why cancer therapies do not work in some patients,” says co-author Hugo Aerts from Mass General Brigham Hospital.

Also interesting: How strongly and quickly the thymus gland breaks down also seems to be related to lifestyle. So the immune organ shrank

• smokers,
• overweight
• and people with elevated cholesterol levels

faster, as the CT scans showed. This means: We can influence to a certain extent how long our thymus remains active.