Study: the forgotten thymus organ could predict lifespan
Mass General Brigham researchers used artificial intelligence to read CT scans of tens of thousands of adults and found that a healthier thymus tracks with a longer life.
- A Mass General Brigham team used artificial intelligence to read CT scans of tens of thousands of adults.
- People with a healthier thymus lived longer and faced a lower risk of heart disease, cancer and death.
- Among patients on immunotherapy, a stronger thymus tracked with about a 37 percent lower risk of cancer progression.
- The results were published in the journal Nature.
For a long time the thymus has been treated as an organ that loses its purpose after childhood and quietly fades from any conversation about adult health. A new analysis turns that impression around. Researchers at Mass General Brigham used artificial intelligence to measure the state of the thymus on CT scans of tens of thousands of adults, then compared what the images showed with what later happened to those people.
The finding, published in the journal Nature, is straightforward. People whose thymus looked healthier lived longer and faced a markedly lower risk of heart disease, cancer and death. Put another way, an organ most of us never mention could serve as a marker of how much life may still lie ahead.
What did the team actually measure?
The thymus sits behind the breastbone, just above the heart, and in youth it is central to the maturing of immune cells. With age it shrinks in most people and turns partly into fatty tissue, but not in everyone at the same pace. Those differences are exactly what the team set out to capture.
Rather than ordering new imaging, the researchers reached for CT scans that already existed, taken for all sorts of medical reasons. The artificial intelligence rated the appearance of the thymus on each scan, and those ratings were then linked to later health outcomes across tens of thousands of adults. A sample that large made it possible to spot patterns that a single clinician would struggle to notice.
The cancer treatment part is especially striking. Among patients on immunotherapy, a stronger thymus tracked with about a 37 percent lower risk of the disease progressing and about a 44 percent lower risk of death. That fits, since immunotherapy relies on the body’s own ability to attack a tumour, and the thymus is part of that immune machinery.
The findings show the thymus is far more important for a long life and for the response to cancer treatment than previously thought, Mass General Brigham said in a statement marking the publication of the study.
What does this study not yet prove?
It pays to be precise. The study shows that a healthier thymus is associated with better outcomes, but it does not prove that the organ causes them. A healthier thymus may travel alongside a range of other favourable circumstances, from general fitness to lifestyle, which would make it more a marker than a driver.
There is also the question of the sample. The scans came from people who had a CT for some reason already, which is not the same as a randomly chosen population. Before a thymus score enters everyday practice, it will need checking in other groups of patients and a clear definition of what counts as a healthy versus a weakened organ.
What does hold is the direction of travel. If the findings are confirmed, a cheap and readily available read of an organ already visible on millions of existing scans could become a useful signal of who carries higher risk. How much would it mean to you if a scan you had already taken could tell you something about how to protect your health in time?
