The Forgotten Organ Is Key to Deep Old Age

The thymus, also known as the thymus gland, has for decades been considered an organ whose role ends with childhood. Due to its gradual shrinkage and replacement by fatty tissue during aging, the prevailing view was that it no longer serves a significant function in adulthood. New research, published in the prestigious journal Nature, now seriously challenges this assumption.

According to scientists, the health of the immune system could be assessed based on the condition of the thymus, which could be one of the important indicators. Their findings suggest that the health of this organ is linked to a longer lifespan, a lower risk of developing cancer and cardiovascular disease, as well as a better response to treatment.

Analysis of Data from 27,000 Participants

To investigate the role of the thymus in adulthood, a research team led by oncologist Dr. Hugo Aerts from Harvard analyzed health data from more than 27,000 individuals. The data were collected as part of two large long-term studies conducted in the United States: the Framingham Heart Study and the National Lung Cancer Screening Program.

All participants underwent computed tomography (CT), and an artificial intelligence-based system assessed the size, structure, and preservation of their thymus. Based on this data, participants were classified into groups with good, average, or poor thymus health, after which scientists tracked their health outcomes over several years.

Impressive Numbers: Lower Risk of Death, Cancer, and Heart Disease

The results showed a surprisingly strong association. Even after accounting for factors such as age, sex, and smoking, individuals with a healthier thymus had approximately 50 percent lower risk of death over the following 12 years compared to those with a deteriorated thymus.

At the same time, the risk of developing lung cancer was about 36 percent lower, and the likelihood of dying from the disease was nearly halved. Even more pronounced differences were observed for cardiovascular diseases: in the two analyzed populations, the risk of death from heart and vascular diseases was between 63 and as much as 92 percent lower in individuals with a better-preserved thymus.

Another study, also published in Nature, indicated a link to the success of immunotherapy. Those with better thymus health had a more successful response to cancer therapies, such as for lung cancer, melanoma, and breast cancer, and on average also had a longer lifespan.

Why Is the Thymus So Important?

Although the thymus shrinks with age, scientists now believe it continues to produce new T lymphocytes, which are crucial for fighting viruses, bacteria, and tumor cells. This view is supported by a 2023 study that found individuals who had their thymus surgically removed had a significantly higher risk of death within five years.

The analysis also showed that smoking, obesity, and chronic inflammation are associated with poorer thymus health. This points to a bidirectional relationship: a healthy thymus can improve the body's defenses, while unhealthy habits can accelerate its decline and reduce the immune response.

Cautious Optimism and the Future of Medicine

The study authors emphasize that the results show an association but do not yet prove that a healthy thymus directly prolongs life or reduces disease risk. To confirm a causal link, further research will be necessary.

Nevertheless, the potential of this discovery is enormous. "If future research confirms these findings, assessing thymus health could become as important as routinely assessing heart or kidney function today. It's possible we've been neglecting an organ that plays a much larger role than we believed," concluded Dr. Aerts, head of the Artificial Intelligence in Medicine Program at Mass General Brigham.

"We knew the thymus in adults was probably not completely inactive, but we were surprised by how strongly its condition and health outcomes are linked," said Dr. Hugo Aerts, an oncologist at Harvard.