The effect of aerobic exercise on tumour blood delivery: a systematic review and meta-analysis.

PURPOSE: Tumour blood vessels are structurally and functionally abnormal, resulting in areas of hypoxia and heterogeneous blood supply. Aerobic exercise may modulate tumour blood flow and normalise the tumour microenvironment to improve chemotherapy delivery. This systematic review and meta-analysis aimed to evaluate the effect of the aerobic exercise mode on tumour hypoxia, vascularisation and blood flow. METHODS: Four online databases were searched. Preclinical and clinical randomised controlled trials examining the effects of aerobic exercise training on hypoxia, vascularisation or blood flow in solid tumours were included. The risk of bias was assessed and a meta-analysis performed. RESULTS: Seventeen preclinical studies and one clinical study met criteria. Eleven studies assessed hypoxia, 15 studies assessed vascularisation and seven evaluated blood flow. There was large variability in measurement methods, tumour types and exercise program designs. The overall risk of bias was unclear in clinical and preclinical studies, owing to poor reporting. There was no significant effect of aerobic exercise on hypoxia (SMD = -0.17; 95% CI = -0.62, 0.28; I2 = 60%), vascularisation (SMD = 0.07; 95% CI = -0.40, 0.55; I2 = 71%) or blood flow (SMD = 0.01; 95% CI = -0.59, 0.61; I2 = 63%). CONCLUSION: There is heterogeneity in methodology, resulting in evidence that is inconsistent and inconclusive for the effects of aerobic exercise on hypoxia, vascularisation and blood flow. Most evidence of aerobic exercise effects on tumour blood flow is in animal models, with very limited evidence in humans.

Aerobic exercise during chemotherapy infusion for cancer treatment: a novel randomised crossover safety and feasibility trial.

PURPOSE: Exercise is a powerful adjunct therapy for patients diagnosed with cancer which can alleviate treatment side-effects and improve a range of outcomes including fatigue and health-related quality of life. Recently, preclinical evidence has suggested that if exercise is performed during chemotherapy infusion, there is enhanced perfusion that may improve drug delivery and attenuate the hypoxic microenvironment. This study aimed to determine the safety and feasibility of delivering an aerobic exercise intervention to cancer patients during chemotherapy infusion. METHODS: A randomised crossover trial was conducted for adults (18-60) undergoing chemotherapy treatment with non-vesicant agents for cancer. In randomised order, during two consecutive chemotherapy infusions, participants either received usual care or performed 20 min of supervised low-intensity cycling. RESULTS: Sixty-five percent of patients approached agreed to participate, and exercise was safely delivered with neither adverse events nor interference to treatment reported for all participants with a mixed cancer diagnosis (N = 10, 90% female, 51.2 ± 7.4 years). There were no significant differences between exercise and usual care in participant-reported difficulty or comfort levels, but exercise significantly reduced boredom (p = 0.01). No significant differences were detected in the symptoms experienced following either intervention. CONCLUSIONS: Exercise during chemotherapy infusion appears to be safe and feasible. Further research is required with a larger sample size to evaluate the impact on tumour perfusion, symptom experience, and opportunity for physical activity increase.