Updated: Jun 7, 2020
Improvements in screening, diagnosis, and treatments of cancer have resulted in an exponential increase in the number of cancer survivors alive in the United States and other industrialized nations. Within the United States, it is estimated there are 15.5 million cancer survivors. The estimate is that there will be a substantive increase in this number over the coming years.  Part of the reason for the increased survival rates is early detection and diagnosis, but studies indicate that exercise can also help fight and prevent cancer.
Unique study in Australia
In a study done in Australia, doctors prescribed targeted exercise to cancer patients. Patients literally left their chemo chair and went straight to an onsite gym. The Exercise Medicine Research Institute (Institute) in Joondalup, Australia is the world’s first gym built right inside a cancer treatment center. 
When a person undergoes chemotherapy, they typically lose weight and have extreme fatigue. Oncologists in Western Australia who sent their patients to the Institute started asking the Institute Director why he was waiting until patients were not feeling well before he started them on an exercise routine. Oncologists thought it might be better to have patients exercise directly after their chemo treatment. There are a growing number of research studies that indicate that people who exercise double their chance of survival. 
The patients in the study felt better after exercising, even though they had just come from having chemotherapy. They experienced less fatigue and their nausea was curbed. Their blood counts were better, and their sense of well-being improved.
The fat, muscle, and bone density of each patient was checked before and after the study. A patient undergoing chemotherapy usually has a decline in muscle mass of around 10– 15%. Researchers were astounded to find that all 38 patients in the trial had no loss of muscle mass and some patients even gained muscle mass!
A Bit of Science
For patients with tumors, it is difficult to get the chemo drugs inside the tumor because tumors notoriously have poor blood supply. Exercise increases blood flow, and exercising right after chemotherapy means you are increasing the circulation of blood and thus delivering more of the chemo drug into the tumor.
What does exercise do to the immune system? Our bodies are making potential cancer cells all the time, but our immune system regularly finds them and destroys them. The trouble with chemo is that it wrecks our immune systems because it kills the good AND bad cells.
Swedish study shows exercise suppresses cancer cell growth
A study done in Sweden in 2013, took a group of 10 healthy young men and had them exercise on a bike for 60 minutes. Their blood was taken before and after they exercised. The blood was spun down to extract the clear serum and poured over laboratory lines of prostate cancer cells to see if they would grow. Surprisingly, the serum taken straight after exercise suppressed cancer cell growth by 30%. 
Denmark study shows exercise shrinks tumors
Another study done in Denmark in 2016 involved mice with cancer. The mice were split into two groups. One had access to a running wheel; the other did not. To be consistent, scientists tried the experiment with mice that had five different types of cancer, from lung cancer to liver cancer to melanoma. If you look at the photo below, which are from the mice with lung cancer (the black stains are the tumors), you will see the difference. The ones that exercised had their tumors reduced by 60-70%. 
And, inside the tumors, photo below, you will see the tumors are chock full of natural killer cells. 
Danish researchers were able to demonstrate how exercising made the difference. What signal were they releasing to make the natural killer cells attack the cancer? Here are two of the most important ones:
Adrenaline – Activates the natural killer cells to flood the blood stream. They are out looking for a target.
Interleukin 6 – When you exercise, your muscles release a chemical called Interleukin 6 (IL6). IL-6 is an interleukin that acts as both a pro-inflammatory cytokine and an anti-inflammatory myokine. IL-6 not only seeks out the tumors directly, but IL-6 also tells the natural killer cells what to target. 
There are many other physiological mechanisms involved, but this study shows how exercise elevates our immune system and make it better at fighting cancer. The body is generating its own anti-cancer drugs. 
What these trials show is that there is clear biological evidence for the cancer-related health benefits of exercise. While more research is needed, doctors should encourage cancer patients and survivors to engage in exercise programs.
If you or someone you know has cancer and would like us to develop a targeted exercise routine, please contact us.