Physical exercise affects the tumor and reduces cancer mortality due to changes in the metabolism of immune cells, demonstrated by experiments. Loads force cells to be more active, which has a positive impact on the ability of the body’s own strength to withstand disease.

Previous studies have shown that physical activity improves the prediction of survival in people with cancer. Scientists knew that this positive effect is due to “strengthening” the ability of the immune system to prevent and suppress the growth of cancer, but the exact biological mechanisms were unknown.

In new experiments, scientists at the Karolinska Institute studied cytotoxic T-lymphocytes, which were aimed at destroying malignant cells. For this purpose, one group of mice could regularly train – running in a wheel, while the other group remained passive.

Slower cancer growth and reduced mortality were observed only in rodents with regular exercise.

Then, scientists administered antibodies to all the rodents, which removed the T cells. This neutralized the positive effect of exercise. If the scientists injected T cells from mice in the first group to the rodents in the second group, this improved their prognosis compared to those who received T cells from physically inactive animals.

In order to assess the impact of the exercises on cancer growth, the scientists studied samples of T-cells, blood and tissue in the animals after training. They measured the levels of metabolites that are produced in muscles in large quantities during exercise and then released into the bloodstream. Some of these metabolites can affect the T-cells, the scientists explain. Experiments have shown that the metabolism of T cells in physically active mice differed from the metabolism of inactive mice.

To evaluate these processes in humans, the scientists analyzed blood samples in healthy men after intensive 30-minute training. It turned out that they were producing the same metabolites.

“Physical exercise affects the production of some molecules and metabolites that activate the immune cells attacking cancer and thus inhibit the growth of cancer,” concluded the co-author of the study Helen Rundquist.

The results provide a better understanding of the impact of lifestyle on the immune system and will improve immunotherapy tools against cancer in the future, she added.