Should patients be exercising immediately before receiving radiation or chemotherapy?
This is a very interesting question because while we do not have any definitive human trials there is compelling theoretical mechanisms supported by preclinical (animal) research. To briefly explain, tumours generally have low blood circulation and thus oxygen level, they are said to be hypoxic. This is a problem when treating a cancer patient with chemotherapy as the blood flow and this delivery of the anti-cancer chemicals into the tumour is compromised. In terms of radiation therapy, effectiveness in terms of cancer cell death is improved with higher levels of oxygen in the tumour.
It has been established in a preclinical (animal) model of prostate cancer that tumour blow flow in vivo increased by 200% with treadmill running and the number of perfused blood vessels with hypoxia decreased by around 50% (1). A later study (2) confirmed this with 180% increase in blood flow. So in mice at least acute bouts of exercise definitely increase blood perfusion within tumours.
To date only one study (3) has investigated the effect of exercise in combination with RT on treatment outcomes and this was again an animal study. There are no human trials of exercise and RT examining the effect on treatment outcomes as yet. In this study it was reported that the combination of exercise and RT increased tumour vascularisation, natural killer cell infiltration and activity resulting in increased tumour cell apoptosis.
Unfortunately, as of March 2020 there was only one study in humans examining exercise effects on tumour vasculature (4). The patients had pancreatic cancer and the researchers compared 23 patients in an exercise trial to 13 historical controls. Total number of vessels, the number of elongated vessels, microvessel density as well as the number of open vessel lumens were all higher in the exercise patients compared to controls.
- McCullough DJ, Stabley JN, Siemann DW, Behnke BJ. Modulation of blood flow, hypoxia, and vascular function in orthotopic prostate tumors during exercise. J Natl Cancer Inst 2014; 106(4): dju036.
- Garcia E, Becker VG, McCullough DJ, Stabley JN, Gittemeier EM, Opoku-Acheampong AB et al. Blood flow responses to mild-intensity exercise in ectopic vs. orthotopic prostate tumors; dependence upon host tissue hemodynamics and vascular reactivity. J Appl Physiol 2016; 121(1): 15-24.
- Dufresne S, Gueritat J, Chiavassa S, Noblet C, Assi M, Rioux-Leclercq N et al. Exercise training improves radiotherapy efficiency in a murine model of prostate cancer. FASEB J 2020; 00: 1-13.
- Florez Bedoya CA, Cardoso ACF, Parker N, Ngo-Huang A, Petzel MQ, Kim MP et al. Exercise during preoperative therapy increases tumor vascularity in pancreatic tumor patients. Sci Rep 2019; 9(1): 13966.
How do we use this information?
- Chronic exercise is likely to normalise microvessel structure in tumours increasing blood flow and oxygenation at rest and during exercise.
- Acute exercise is likely to increase blood flow and oxygenation in tumours in humans by a factor of 2-3x.
- Cancer patients should exercise throughout their cancer treatment.
- Immediately before receiving chemotherapy or radiation therapy, patients may benefit from an acute bout of exercise into boost blood flow and oxygenation within their tumour and potentially increase the effectiveness of therapy.
How do we implement this strategy?
First up, there is no down-side to performing an acute bout of exercise immediately before therapy apart from getting perhaps a little sweaty. If nothing else it will help reduce anxiety before and during the treatment.
- exercise dose of 10-20 minutes of vigorous exercise is likely sufficient
- try to time so as close to commencement of therapy as possible – the effects are transient
- would be great if the cancer centre has a treadmill or stationary bike in the waiting room but otherwise…
- try stair climbing or stepping up and down a step in place.
- resistance training exercises including activating the muscles near to the site of the cancer
- For example, for pelvic region cancers, squat, lunge, deadlift…
There will be definitive results from clinical trials in the near future to quantify the effectiveness of acute exercise bouts and whether this enhances treatment effectiveness or not. In the meantime, it is probably a good bet to give this a try.
Clinicians with MyExerciseMedicine subscription can access sample acute exercise programs for pre chemo and radiation therapy treatment from our Exercise Prescriptions Section.