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The role of circulating miRNAs (c-miRNAs) in carcinogenesis has garnered considerable scientific interest. miRNAs may contribute actively to cancer development and progression, making them potential targets for cancer prevention and therapy. Lifestyle factors such as physical activity (PA) have been shown to alter c-miRNA expression, but the subsequent impact on cancer risk and prognosis is unknown. To provide a better understanding of how PA reduces the risk of cancer incidence and improves patient outcomes, we conducted a review of the impact of PA on c-miRNA expression, which includes a comprehensive synthesis of studies examining the impacts of acute and chronic exercise on expression of c-miRNAs. While the variability in methods used to assess miRNA expression creates challenges in comparing and/or synthesizing the literature, results to date suggest that the circulating form of several miRNAs known for playing a role in cancer (c-miR-133, c-miR-221/222, c-miR-126, and c-let-7) are altered by both acute and chronic PA. Additional research should develop standardized procedures for assessing both c-miRNA and PA measurement to improve the comparability of research results regarding the direction and amplitude of changes in c-miRNAs in response to PA. .

Engaging in exercise while undergoing radiotherapy (RT) has been reported to be safe and achievable. The impact of exercise training (ET) on RT efficiency is however largely unknown. Our study aims to investigate the interactions between ET and RT on prostate cancer growth. Athymic mice received a subcutaneous injection of PPC‐1 cells and were randomly assigned to either cancer control, cancer ET, cancer RT, or cancer RT combined with ET (CaRT‐ET). Mice were sacrificed 24 days post‐injection. All three intervention groups had reduced tumor size, the most important decrease being observed in CaRT‐ET mice. Apoptotic marker cleaved caspase‐3 was not modified by ET, but enhanced with RT. Importantly, this increase was the highest when the two strategies were combined. Furthermore, NK1.1 staining and gene expression of natural killer (NK) cell receptors Klrk1 and Il2rβ were not affected by ET alone but were increased with RT, this effect being potentiated when combined with ET. Overall, our study shows that (a) ET enhances RT efficiency by potentiating NK cell infiltration, and (b) while ET alone and ET combined with RT both reduce tumor growth, the mechanisms mediating these effects are different.

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