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A new study suggests melanoma may spread most aggressively during middle age rather than old age
Cancer does not always behave in a straight line with age, and a new study suggests melanoma may actually be most aggressive during middle age, before its spread slows again in later life.
According to research highlighted by Temple University Health System and Fox Chase Cancer Center, melanoma’s ability to spread appears to follow a surprising pattern linked to changes in the immune system over time.
The findings were presented at the American Association for Cancer Research annual meeting and published in Cancer Research under the title “Role of Aging on the γδ T-cells in Metastatic Cutaneous Melanoma Progression.”
The study found that cancer spread was lowest in young subjects, sharply increased in middle age, and then declined again in very old age, challenging the long-held assumption that cancer risk and aggressiveness simply rise with age.
Researchers believe the pattern may be tied to a specialized group of immune cells known as gamma delta (γδ) T cells, which play an early role in defending the body against abnormal cell growth and preventing cancer from spreading.
In younger and very old subjects, higher levels of these protective immune cells were observed, helping keep tumors more contained or less aggressive.
In contrast, middle-aged subjects showed a noticeable decline in γδ T cells, which coincided with a greater likelihood of melanoma spreading to vital organs such as the lungs and liver.
The study suggests that this temporary dip in immune protection during middle age may create a window in which melanoma gains a stronger foothold before immune activity changes again in later years.
Researchers also highlighted a broader issue in cancer science: fewer than 10% of mouse studies use aged animals.
Instead, most experiments rely on younger models that roughly reflect humans in their early twenties.
Scientists warn that this gap could help explain why some treatments that appear effective in the lab fail in real-world clinical trials.
By failing to fully account for how the immune system changes with age, researchers may be overlooking critical factors that influence how cancers behave in different stages of life.
The findings underscore the importance of including older biological models in cancer research, particularly when studying diseases that disproportionately affect aging populations.