The role of immune system in fighting cancer is well-documented, with specific immune cells known to attack and destroy tumor cells. However, the impact of acute exercise on the mobilization of these immune cells in cancer patients has remained largely unexplored. In a groundbreaking study, researchers from the University of Turku have discovered that a simple 30-minute exercise session can significantly enhance the mobilization of certain immune cells in breast cancer patients, potentially improving the body’s ability to combat tumor cells.
Breast cancer ranks as the most frequently diagnosed cancer in women and is the second leading cause of cancer-related deaths among women globally. The frequency of breast cancer rises with age, starting from 1.5 cases per 100,000 in women aged 20 to 24, and reaching a peak of 421.3 cases per 100,000 among those aged 75 to 79. Approximately 95% of new cases occur in women aged 40 years and older. The median age at which women are diagnosed with breast cancer is 61 years. The predominant form of breast cancer is ductal carcinoma, originating in the lining of the milk ducts.
Nineteen breast cancer patients, aged between 36 and 68, participated in the study. The patients performed 30 minutes of moderate-intensity exercise on a cycle ergometer. Blood samples were collected at multiple time points: at rest, 15 minutes (E15) and 30 minutes (E30) after starting the exercise, and at 30- and 60-minutes post-exercise. The researchers analyzed various immune cell subsets using flow cytometry, a powerful technique for examining the characteristics of cells.
The study findings showed that acute exercise led to a significant increase in the number of several types of immune cells, including total leukocytes, neutrophils, lymphocytes, monocytes, basophils, total T-cells, CD4+ T-cells, T helper (Th) 2-cells, Th 17-cells, CD8+ T-cells, CD4-CD8- T-cells, CD56+ natural killer (NK) cells, and CD14-CD16+ monocytes. Many of these changes were transient, highlighting the dynamic nature of the immune response to exercise. Notably, the study revealed that the proportions of NK-cells and CD8+ T-cells increased, while the proportion of myeloid-derived suppressor cells (MDSCs) decreased. Regulatory T-cells remained unchanged by exercise.
The researchers also investigated whether different types of breast cancer influence how white blood cells respond to exercise. They found that larger tumors were associated with less increase in natural killer cells, and in estrogen and/or progesterone receptor-positive breast cancers, the increase in cytotoxic T cells was less pronounced compared to hormone receptor-negative cancers.
Physical exercise has been shown to prevent cancer, reduce the side effects of cancer treatments, and improve both prognosis and quality of life for patients. For instance, individuals who are most physically active during their leisure time have a 13% lower risk of being diagnosed with breast cancer compared to those who are least active. Additionally, cancer-specific mortality is 31% lower in physically active individuals’ post-diagnosis compared to their sedentary counterparts.
Tumor immune surveillance involves a delicate balance between immune cells that promote tumor progression (pro-tumorigenic cells) and those that promote tumor rejection (anti-tumorigenic cells). Studies using animal cancer models have demonstrated that exercise can shrink tumors by enhancing the infiltration of anti-tumorigenic cells, such as natural killer (NK) cells and cytotoxic T cells, into the tumor. Moreover, exercise has been found to reduce the accumulation and recruitment of pro-tumorigenic MDSCs and regulatory T cells in breast cancer tumors in mice. These findings underscore the potential of physical activity as a beneficial intervention in cancer prevention and treatment.
Reference
- Frontiers | The effect of exercise and disease status on mobilization of anti-tumorigenic and pro-tumorigenic immune cells in women with breast cancer [Internet]. [cited 2024 Jul 6]. Available from: https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2024.1394420/full
- Menon G, Alkabban FM, Ferguson T. Breast Cancer. In: StatPearls [Internet]. Treasure Island (FL): Stat Pearls Publishing; 2024 [cited 2024 Jul 6]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK482286/
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- Definition of breast cancer – NCI Dictionary of Cancer Terms – NCI [Internet]. 2011 [cited 2024 Jul 6]. Available from: https://www.cancer.gov/publications/dictionaries/cancer-terms/def/breast-cancer