When we think about the benefits of physical activity, cancer prevention and improved treatment outcomes are often not the first things that come to mind. You might even be surprised to learn that exercise can help reduce cancer risk and improve the effects of other, more traditional, treatments like chemotherapy.
Let’s first take a look at cancer risk reduction.
How does physical activity reduce the risk of developing cancer?
A growing body of research is emerging in support of this connection. An intriguing paper by Moore et al. (2016) discusses various types of cancer for which leisure-time physical activity has been shown to reduce risk, including lung, breast, and colon cancers, among others.
While we don’t fully understand the mechanisms behind the reduced cancer risk associated with increased physical activity, several potential pathways have been suggested.
First, exercise helps break down fat stores in the body and reduces adipose tissue. Fat cells contribute to altered levels of certain hormones in the body which, down the line, have an effect on risk of cancer development. A few of these hormones and their potential impact on the body are highlighted below.
When adipose tissue accumulates, it releases higher levels of oestrogen, which has been linked to increased risks of breast, ovarian, and endometrial cancers. Additionally, people with obesity often have elevated levels of insulin and a hormone called insulin-like growth factor-1 (IGF-1). Higher levels of these hormones can indicate insulin resistance, which may lead to type II diabetes – a known risk factor for cancer.
Exercise also plays a role in reducing systemic inflammation. Obesity tends to elevate baseline inflammation levels slightly but chronically. This increase in inflammation can alter cell structures in the body (due to oxidative stress and the production of free radicals), potentially heightening cancer risk.
Moreover, physical activity can enhance immune function by mobilizing more immune cells, enabling the body to target and eliminate cancer cells before they multiply.
It’s important to note that Moore et al. (2016) found an increase in prostate cancer and malignant melanoma associated with physical activity. The authors suggest that the increase in prostate cancer cases may be due to screening bias, as active men are more likely to undergo prostate examinations, leading to more detected cases in this group. However, they acknowledge that this remains speculative and that causality cannot be determined.
The link between physical activity and an increased risk of malignant melanoma is perhaps more intuitive. Individuals who engage in leisure-time physical activity are likely to spend more time outdoors, increasing their UV exposure and, consequently, the risk of skin cancers. So don’t forget to apply sunblock if you’re working out outside!
We’ve established that exercise plays a key role in cancer prevention, but how much should we actually be doing to maximize its benefits?
How much exercise should we be doing to reduce our risk of cancer?
The American Cancer Society recommends that adults engage in at least 150 to 300 minutes of moderate-intensity physical activity, or 75 to 150 minutes of vigorous-intensity activity (or a combination of both) each week. Ideally, they suggest aiming for 300+ minutes of physical activity weekly. Additionally, they recommend including resistance training sessions a couple of times per week.
Incorporating planned physical activity into your routine is a great first step. However, it’s also important to reduce the time spent sitting each day. This means finding ways to move more and sit less. If you have a desk job, consider using a standing desk or even investing in an under-desk treadmill to help boost your step count while you work!
For those planning ahead for their children’s health, it’s recommended that youngsters get at least an hour of physical activity each day. This should include aerobic activity, muscle-strengthening exercises at least three times a week, and bone-strengthening activities at least three times a week.
If all this sounds a bit overwhelming, don’t worry. Yes, ideally we should aim for 30 minutes to an hour of exercise a day, combining both aerobic and strength-based activities, while also minimizing sitting time. But for many of us, making such changes may feel like a big adjustment. The good news is that any amount of physical activity – no matter how small – will already help reduce your risk of developing chronic health conditions, including cancer.
If you’re currently not active, start small: take the stairs at work, add a couple of gym sessions into your week, or even take a short walk daily. Everyone has to start somewhere, and even a little exercise is far better than none (Rock et al., 2020). So, remember: move more and sit less!
Let’s now shift our focus slightly, and discuss how physical activity can help those already fighting cancer.
How does physical activity help those currently battling cancer?
Not only can staying active reduce your risk of developing cancer, but it can also serve as an adjunct to other therapies for those battling the disease. Research indicates that those who exercise may experience reduced fatigue from cancer treatments and have a greater tolerance for chemotherapy, enabling them to successfully complete their treatment and perhaps even receive higher doses that are potentially more effective against cancerous cells (Brown et al., 2012).
Additionally, exercise can improve tumour perfusion. Tumours, like other tissues, rely on a blood supply, however, their blood vessels are often weak and may not reach all tumour cells. This can lead to hypoxia, where some cells may mutate and proliferate. Exercise can strengthen the blood vessels in tumours, enhancing oxygenation, preventing hypoxia, and providing a more effective system for delivering chemotherapy directly to the heart of the tumour (Schadler et al., 2016).
If you’re currently battling cancer, consider joining an exercise-based support group. In the UK, Macmillan Cancer Support organise Bounce Back Exercise classes, led by a Level 4 Cancer Rehabilitation Exercise professional. These classes are so much more than a workout. They’re a great way to meet others on a similar journey, support one another and, yes, incorporate some physical activity into your weekly routine. Working out has also been shown to boost mental wellbeing, so attending a class could help reduce any stress and anxiety you might be feeling and improve your mood (Brown et al., 2012). As with any situation in which you’re planning to change your activity levels, please consult with a medical professional beforehand.
Finally, how can exercise help cancer survivors?
How can exercise help those who’ve won the battle?
Unfortunately, after battling the disease, cancer survivors tend to experience a range of challenges, including fatigue, pain, reduced immune function, decreased cardiovascular fitness and sometimes obesity (Sabiston & Brunet, 2011). We have already discussed how exercise can help improve immune function, reduce adiposity and attenuate fatigue in previous sections. Similarly, it has been shown that exercise can be beneficial in dealing with these issues in cancer survivors and physical activity appears to be safe for this group to engage in (Sabiston & Brunet, 2011). Reversing the physical deconditioning that sometimes takes place in cancer patients is important to boost general health and fitness, and exercise can be used as a means for doing this. Most importantly, physical activity has been linked to lower cancer recurrence and mortality rates in cancer survivors (Brown et al., 2012), so it really is a great tool to continue fighting the disease and prevent its return!
Conclusion
Maintaining a healthy weight is important for reducing cancer risk (Freidenreich & Orenstein, 2002). However, Moore et al. (2016) note that staying active can mitigate risk regardless of body size. So even if you’re struggling to shed those extra pounds, don’t lose hope! Working out can provide significant health benefits on its own. While more than 300 minutes of exercise a week is recommended for the greatest reduction in cancer risk, any amount of physical activity is better than none, so just try to move more and sit less.
Disclaimer
The author is not a medical professional, but an exercise physiology PhD candidate. Before starting or changing your exercise routine – especially if you are undergoing cancer treatment – it’s important to discuss your plans with a healthcare professional or your doctor.
References
Brown, J. C., Winters-Stone, K., Lee, A., & Schmitz, K. H. (2012). Cancer, Physical Activity, and Exercise. Comprehensive Physiology, 2(4). https://doi.org/10.1002/cphy.c120005
Cancer Research UK. General cancer organisations. Retrieved January 21, 2025, from https://www.cancerresearchuk.org/about-cancer/coping/general-books-links/general-cancer-organisations
Friedenreich, C. M., & Orenstein, M. R. (2002). Physical Activity and Cancer Prevention: Etiologic Evidence and Biological Mechanisms. The Journal of Nutrition, 132(11), 3456S3464S. https://doi.org/10.1093/jn/132.11.3456s
Macmillan Cancer Support. Bounce Back Exercise. Retrieved January 21, 2025, from https://www.macmillan.org.uk/in-your-area/local-dashboard-detail.html?id=11328&typeDisplayName=Practical+help+and+support+groups&itemName=Bounce-Back-Exercise&proximity=6.80+miles+from+you&ui=pc#:~:text=Practical%20help%20and%20support%20groups&text=From%20Balance%20and%20Gait%20Training,disease%20symptoms%20and%20side%20effects.
Moore, S. C., Lee, I-Min., Weiderpass, E., Campbell, P. T., Sampson, J. N., Kitahara, C. M., Keadle, S. K., Arem, H., Berrington de Gonzalez, A., Hartge, P., Adami, H.-O., Blair, C. K., Borch, K. B., Boyd, E., Check, D. P., Fournier, A., Freedman, N. D., Gunter, M., Johannson, M., & Khaw, K.-T. (2016). Association of Leisure-Time Physical Activity With Risk of 26 Types of Cancer in 1.44 Million Adults. JAMA Internal Medicine, 176(6), 816–825. https://doi.org/10.1001/jamainternmed.2016.1548
National Cancer Institute. (2022, April 5). Obesity and Cancer. National Institutes of Health. https://www.cancer.gov/about-cancer/causes-prevention/risk/obesity/obesity-fact-sheet#:~:text=Fat%20tissue%20(also%20called%20adipose,1%20(IGF%2D1).
Rock, C. L., Thomson, C., Gansler, T., Gapstur, S. M., McCullough, M. L., Patel, A. V., Andrews, K. S., Bandera, E. V., Spees, C. K., Robien, K., Hartman, S., Sullivan, K., Grant, B. L., Hamilton, K. K., Kushi, L. H., Caan, B. J., Kibbe, D., Black, J. D., Wiedt, T. L., & McMahon, C. (2020). American Cancer Society guideline for diet and physical activity for cancer prevention. CA: A Cancer Journal for Clinicians, 70(4). https://doi.org/10.3322/caac.21591
Sabiston, C. M., & Brunet, J. (2011). Reviewing the Benefits of Physical Activity During Cancer Survivorship. American Journal of Lifestyle Medicine, 6(2), 167–177. https://doi.org/10.1177/1559827611407023
Schadler, K. L., Thomas, N. J., Galie, P. A., Bhang, D. H., Roby, K. C., Addai, P., Till, J. E., Sturgeon, K., Zaslavsky, A., Chen, C. S., & Ryeom, S. (2016). Tumor vessel normalization after aerobic exercise enhances chemotherapeutic efficacy. Oncotarget, 7(40), 65429–65440. https://doi.org/10.18632/oncotarget.11748