Most people have never heard of the thymus, and even many scientists paid relatively little attention to it for years.
The organ is small, sits behind the breastbone, and gradually shrinks as people grow older. Because of this natural shrinking process, many experts assumed it had little influence on adult health.
A pair of new studies from researchers at Mass General Brigham suggests that assumption may have been wrong. The research indicates that the thymus could be one of the most important organs involved in healthy aging, disease prevention, and even cancer treatment success.
The findings were published in Nature and are attracting attention because they challenge decades of scientific thinking.
The thymus plays a critical role in the immune system. During childhood and early adulthood, it helps create and train T cells. These cells act like security guards that patrol the body looking for infections, viruses, and abnormal cells that may become cancerous.
As people age, the thymus becomes smaller and contains more fatty tissue. Scientists long believed this shrinking meant the organ had largely completed its job. However, the new studies suggest that differences in thymus health continue to matter throughout adult life.
To investigate this question, researchers turned to large health databases containing medical information from thousands of people. One group included more than 25,000 adults who took part in a lung cancer screening program. Another group came from the Framingham Heart Study, one of the most influential long-term health studies ever conducted.
The researchers used artificial intelligence to analyze CT scans. The computer system examined the appearance of the thymus and measured characteristics such as its size and composition. These measurements were combined into a score that reflected overall thymic health.
The scientists then compared thymic health scores with health outcomes over time.
People with healthier thymuses consistently performed better. They were less likely to die from any cause, less likely to die from cardiovascular disease, and less likely to develop lung cancer.
One of the most remarkable findings was the size of the difference. Individuals with healthier thymuses had roughly half the overall risk of death compared with those who had poorer thymic health.
The results suggest that the thymus may help maintain a stronger and more flexible immune system throughout life. Researchers believe that healthier thymuses may continue producing a wider variety of T cells, giving the body a better chance of identifying and fighting disease.
The studies also provided clues about factors that may harm thymic health. Smoking was linked to poorer thymus condition, as were higher levels of inflammation and excess body weight. These findings fit with previous research showing that smoking and chronic inflammation can damage many parts of the body.
The second study focused on cancer immunotherapy. Immunotherapy has transformed cancer treatment by helping the immune system recognize and attack tumors. However, not every patient benefits equally from these therapies.
Researchers studied more than 1,200 cancer patients receiving immunotherapy and discovered that thymic health appeared to influence treatment success. Patients with healthier thymuses had lower risks of cancer progression and death.
This raises the possibility that doctors may one day use thymic health as a way to predict which patients are most likely to respond to immunotherapy.
The findings could also lead to new research aimed at protecting or preserving thymic function. Scientists are already exploring factors that may affect the organ, including unintended radiation exposure during cancer treatment.
Despite the promising results, the researchers caution that many questions remain unanswered. It is not yet known whether improving thymic health will directly improve survival or reduce disease risk. The studies show strong connections, but they cannot prove that the thymus is solely responsible for the observed benefits.
If you care about medicine, please read studies that vitamin D could help lower the risk of autoimmune diseases, and drug for inflammation may stop spread of cancer.
For more health information, please see recent studies about which drug can harm your liver most, and results showing this drug can give your immune system a double boost against cancer.
Source: Mass General Brigham.
