HELSINKI: In the past, researchers found that exercise destroys cancer cells by increasing the activity of cytotoxic T cells and natural killer cells, but these studies did not investigate whether patients exercised for long periods of time. If so, what happens to the cancer-promoting cells?
A group of researchers in Finland investigated how 30 minutes of exercise affected the ratio of cancer-killing versus cancer-promoting immune cells in the blood of breast cancer patients.
They studied 20 breast cancer patients who had just been diagnosed and had not yet started cancer treatment.
During the study, the team asked patients to pedal a bicycle equipped with an exercise monitor for 30 minutes.
The researchers took blood samples at rest before exercise, at 15-minute and 30-minute time points during exercise, and at 30 minutes and 60 minutes after exercise. The researchers performed blood tests to count the number of different types of immune cells in each patient’s blood sample at different points during exercise.
The researchers found that the number and proportion of different immune cells in the patients’ blood changed during exercise. After 15 minutes of exercise, white blood cells that kill various types of cancer increased by an average of 15 percent to 55 percent, the team reported.
Similarly, the number of cancer-killing cytotoxic T cells and natural killer cells increased by 36% and 154%, respectively, after 15 minutes and remained high after 30 minutes. They also found that the number of cancer-promoting cells decreased from 44 percent to 32 percent after 15 minutes of exercise and 34 percent after 30 minutes of exercise.
