A new study finds that aerobic exercise, such as brisk walking, swimming, running, or cycling, can help reprogram the immune system to reduce tumor growth and enhance the effects of immunotherapy.
The study, which focused on pancreatic cancer, was published online in Cancer Cell and provides new insight into how the mammalian immune system, which is designed to attack foreign invaders like bacteria, can also recognize cancer cells as abnormal.
Exercise helps the immune system
According to New York University researchers, exercise-induced increases in the hormone adrenaline cause changes in the immune system.
It includes cell activity in response to the signaling protein interleukin-15 (IL-15).
The researchers discovered that exercise increases the survival of IL-15-sensitive CD8 T cells and doubles the number of them that homing to pancreatic ductal adenocarcinoma (PDAC) tumors in mice.
Other studies have shown that such "effector" T cells are capable of killing cancer cells. Other studies found that 30 minutes of aerobic exercise five times a week reduced the rate of cancer formation by 50% in one mouse model of PDAC and reduced tumor weight by 25% in another model in which mice ran on treadmills for three weeks.
The researchers then discovered, in collaboration with The University of Texas MD Anderson Cancer Center, that human patients who exercised before surgery to remove pancreatic tumors had more CD8 effector T cells that expressed granzyme B, a protein that confers tumor-cell killing ability.
Patients who exercised and had more of these cell types had a 50% higher overall survival over five years than those who did not.
"For the first time, our findings show how aerobic exercise affects the immune microenvironment within pancreatic tumors," said first author Emma Kurz, a graduate student at NYU Grossman School of Medicine.
"The research contributed to the discovery that activating IL-15 signaling in pancreatic cancer could be an important treatment strategy in the future.”
The research can be found here:
https://www.cell.com/cancer-cell/fulltext/S1535-6108(22)00217-3
