A "neglected" gland plays a much greater role in health than previously thought

A new study has revealed that the thymus gland, long considered largely inactive after childhood, plays a far greater role in health and longevity than previously believed. Researchers found that the size and condition of this small gland, located behind the sternum near the heart, could significantly influence a person's risk of developing serious illnesses such as cancer and cardiovascular disease throughout their entire life. For decades, the thymus was thought to be primarily active during early development, playing a crucial role in training the immune system in children before gradually shrinking and becoming less functional with age. However, recent research challenges this assumption, suggesting that the gland continues to have a meaningful impact on adult health. The findings come from two studies led by oncologist Hugo Aerts of Harvard University, which analyzed health data from over 27,000 participants. Using computed tomography scans, researchers measured the size, shape, and composition of each participant’s thymus. These metrics were fed into a deep learning system designed to assess the overall health of the gland in adults. Based on these assessments, participants were categorized into groups with low, average, or high thymus health. When controlling for factors such as age, sex, smoking status, and existing medical conditions, researchers observed a striking correlation between better thymus health and improved survival rates. Individuals with healthier thymuses had approximately a 50 percent lower relative risk of death within the following 12 years compared to those with poorer thymus function. The risk of developing lung cancer was reduced by around 36 percent among those with healthy thymuses, while the risk of dying from lung cancer was cut by nearly half. Similar reductions in risk were noted for cardiovascular diseases, with one study linking robust thymus health to a 63 percent decrease in mortality from heart-related issues, and another showing up to a 92 percent reduction. Aerts expressed surprise at the strength and consistency of these associations, noting that they suggest the thymus plays a much more significant role in adult health than previously understood. He emphasized that the findings indicate a need to reconsider how the gland functions beyond childhood and its potential implications for treating and preventing disease. While the study highlights strong correlations between thymus health and outcomes, it does not establish causation. Further research will be needed to confirm whether maintaining or improving thymus function directly contributes to better health outcomes. Nevertheless, the results challenge existing assumptions about the gland’s role and open new avenues for understanding the immune system. In addition to the main study, a related investigation published in the journal Nature under Aerts' leadership found that thymus health is also linked to responses to immunotherapy in several types of cancer, including lung cancer, melanoma, breast cancer, and others. This suggests that the gland might play a critical role in supporting the body’s ability to fight disease through the immune response. Researchers are still unsure exactly how the thymus exerts such a profound influence on adult health. However, these findings align with a groundbreaking 2023 study that showed individuals who had undergone surgical removal of their thymus faced higher risks of certain health complications later in life. The implications of these discoveries extend beyond basic science. They suggest that assessing thymus health could help identify patients who would benefit most from specific treatments or allow for personalized approaches to preserving immune function as people age. As scientists continue to explore the mechanisms behind these observations, the thymus may soon be viewed not just as a relic of childhood immunity, but as a vital component of lifelong health.