Does Exercise Prevent Cancer?

Let’s start with the simple fact that a lot of cancer diagnoses are simply down to ‘bad luck’.

You can do everything right and still get cancer.

This is a somewhat depressing fact, given its leading position as a cause of death.

The other leading cause of death, cardiovascular disease, is mostly preventable.

Cancer - Less so.

But that does not mean you cannot tilt the odds in your favour. 

And regular exercise, it seems, might be a good way of doing so.

Regular exercise and high levels of physical fitness have been consistently associated with longer lifespans and a substantially reduced risk of dying from any cause1.

 

If exercise reduces all-cause mortality, it seems safe to say that it is reducing cardiovascular and cancer deaths.

Let’s look at cancer specifically. 

Over a 10-year period, those in the highest fitness levels had an 11% reduction in the risk of cancer2.

But this 11% figure masks the fact that not all cancers are impacted equally.

Exercise has little effect on some cancers, while it has a much bigger effect on others.

While the risk of gastric/stomach cancer is reduced by only about 5%, the reductions in other cancer types are even greater.

• Breast Cancer - 13% Reduction

• Oesophageal Cancer - 18% Reduction

• Liver Cancer - 18% Reduction

• Lung Cancer - 25% Reduction

• Colorectal Cancer - 26% Reduction

The impact of exercise on cancer even extends beyond the original diagnosis and has been shown to reduce the likelihood of recurrence of cancer3.

Regular exercise in those who have already been diagnosed with cancer has been associated with:

• A reduced chance of dying from a breast cancer diagnosis by 40% compared to those with breast cancer who did not exercise regularly4.

• A reduced risk of death from colorectal cancer by 30%5.

The question is WHY exercise might be associated with such benefits with respect to cancer.

Regular exercise and high fitness levels are associated with lower rates of obesity.

Obesity is the second leading cause of preventable cancers after smoking6.

Please reread that line again.

It should hit you like a ton of bricks. If it doesn’t, you are not getting the magnitude of the problem that is preventable. 

The likely driver of the cancer risk conferred by obesity is probably related to higher levels of insulin resistance and metabolic syndrome.

A diagnosis of metabolic syndrome significantly increases your risk of several leading cancers7:

• Postmenopausal Breast Cancer - 52% Increased Risk

• Hepatocellular Cancer - 81% Increased Risk

• Colorectal Cancer - 30-40% Increased Risk

• Pancreatic Cancer - 55% Increased Risk

But insulin resistance and metabolic syndrome are not the only drivers of risk.

Cancer As A Breakdown Of Immune Function

The hallmark of cancer is the uncontrolled replication of cells.

But the cells in your body are continually replicating.

The mechanisms of replication usually do an excellent job at producing exact copies of cells, but sometimes replication errors occur, which can lead to the development of cancer8.

The immune system's job is to constantly search for these poorly replicated cells and destroy them.

In truth, we are probably creating very early cancerous cells throughout our lives, but because of our immune system, they do not get the opportunity to progress into fully formed cancers.

Natural Killer Cells are one of the key agents for targeting abnormal precancerous cells.

A properly functioning immune system then is essential for cancer protection.

Hereditary Cancers and The Role Of The Immune System

Lynch syndrome is a genetic colorectal cancer disorder where 60% of carriers go on to develop colorectal cancer over their lifetime9.

A recent study examined the question of whether regular exercise in such a high-risk group for cancer would impact the number of natural killer cells, which are important tools for destroying early cancer cells.

Those who did 45 minutes of high-intensity exercise three times per week for a year had significantly higher levels of natural killer cells10.

 

The higher levels of natural killer cells are likely to explain at least some of the protection regular exercise confers when it comes to cancer prevention.

Regular exercise also influences a variety of other cellular mechanisms that modulate cancer risk, including beneficial changes in11:

• Cell Growth Regulators - IGF1 & IGFBP3.

• Suppression of RAS oncogenes.

• Higher levels of proteins involved in cellular repair.

• Enhanced activity of regulators of apoptosis and cellular growth.

Tilting Odds

The best way of not dying from cancer is to not get cancer.

Unfortunately, much of that risk is simply down to ‘Bad Luck’.

However, it is clear that regular exercise can play a crucial role in decreasing the odds of developing cancer, and the mechanisms by which it does so are becoming increasingly clear.

We need all the help we can get.

Keep the odds on your side.