Role of physical exercise in modulating the insulin-like growth factor system for improving breast cancer outcomes: A meta-analysis

Background: Physical activity prevents cancer and improves cancer outcomes. Insulin-like growth factor (IGF) signaling plays a significant role in cancer development and progression. However, there are heterogeneous results regarding physical activity and its effect on the IGF system. This study meta-analyzed the results of randomized clinical trials which evaluated the effects of physical exercise on the changes of physiologic markers to identify the role of physical exercise in modulating the IGF system in women with breast cancer. Methods: PubMed, Embase, CENTRAL, and SPORTDiscus were systematically searched until October 2020. Eligibility criteria included randomized controlled trials that evaluated the effects of physical exercise on the insulin-like growth factor system among women with breast cancer. Results: Twelve randomized controlled studies involving 736 participants were analyzed. Physical exercise significantly reduced levels of serum insulin (MD -1.24 mu IU/mL, 95% CI -2.12 to -0.36, p = 0.006), IGF-II (MD -54.21 ng/mL, 95% CI -61.41 to -47.00, p < 0.00001), IGFBP-1 (MD -2.90 ng/mL, 95% CI -3.91 to -1.90, p < 0.00001), and HOMA score (MD -0.47, 95% CI -0.87 to -0.06, p = 0.02). In addition, serum glucose (MD -0.71 mg/dL, 95% CI -2.57 to 1.15; p = 0.45) and IGF-I levels (MD -5.23 ng/mL, 95% CI -13.00 to 2.53; p = 0.19) were decreased after physical exercise although they did not show a statistical significance. Conclusion: Physical exercise had a positive effect on the IGF system in women with breast cancer.

Automated summary

This study analyzed 12 randomized controlled trials involving 736 participants and found that physical exercise significantly reduced levels of serum insulin, IGF-II, IGFBP-1, and HOMA score in women with breast cancer. Additionally, serum glucose and IGF-I levels decreased after physical exercise although they did not show statistical significance.