Monday’s medical myth: stress causes cancer
"But three decades of study have found no direct association between stress and cancer..."
Image: fotografstockholm/iStockphoto

Cancer is a disease of the body’s cells that affects around half of all Australians by the age of 85. Normally cells grow and multiply in a controlled way. But if something causes a mistake to occur in the cells' genetic blueprints, this control can be lost.

There are a number of chemical, physical and biological agents that have been shown to trigger the mistakes in the cell blueprint that cause cancer – but stress isn’t one of them.


We all encounter short- and long-term stresses in our lives, such as work challenges, relationship problems and illness, which have varying degrees of psychological impact. Stress can be nature’s way to help energise us to deal with these adverse events.

But high levels of stress can lead to anxiety and depression. These are serious, often interconnected, mental health problems that can affect your ability to work, maintain relationships and lead a fulfilled life. But three decades of study have found no direct association between stress and cancer, not even when stress is high enough to cause an anxiety disorder or depression.

So if you want to reduce your risk of cancer, the most important thing you can do is avoid or reduce the known risk factors – such as smoking, being overweight, having a poor diet, being physically inactive, exposing yourself to UV radiation and consuming excessive amounts of alcohol. Avoiding these risk factors is known as adopting a “cancer-smart” lifestyle.

Someone who feels stressed but lives a cancer-smart lifestyle is at no higher risk of cancer than a relaxed person with an equally healthy lifestyle. By the same token, a person who doesn’t feel stressed but smokes or does other things that are known to cause cancer is at higher risk than even the most anxious individual who has a cancer-smart lifestyle.

So, in the absence of evidence, why do so many people think stress causes cancer?

One reason could be that people who are stressed tend to smoke, drink excessively, be inactive and have poor diets. But this does not make stress itself a cancer risk factor. (Ironically, tobacco use, physical inactivity, excessive drinking and consumption of “comfort foods” can actually increase, rather than alleviate, stress levels.)

Another reason for the myth might be the relationship between stress and the body’s immune system. There is some evidence that stress can lower immunity – the body’s natural defence against disease. Reduced immunity makes us more susceptible to some virus-related cancers, such as certain forms of lymphoma and Kaposi’s sarcoma. However, evidence of causation is limited and, again, complicated by the direct impact of behavioural risk factors on the immune system.

Studies also show that people who are emotionally distressed are more likely to think they are sick. The flip side is that dealing with serious illnesses like cancer can be stressful. But again, neither equates to stress being a cause of cancer.

The idea that a positive outlook will affect your chances of remission from cancer or your survival is another myth, based on stories we hear about people who “beat” their cancer through their “fighting spirit” or “determination”. There is no conclusive evidence that people who are distressed by their cancer experience have poorer clinical outcomes than those who feel “positive” – provided they follow evidence-based advice on treatment and care.

The perception that some patients did not survive because they were not as positive as others is unfounded and unfair. Dealing with a cancer diagnosis is tough enough; being pressured into thinking that the only way through it is to remain positive and thus minimise your stress can add to a patient’s individual burden.

Stress is, nonetheless, a significant health issue. If it’s a problem for you, you can learn calming techniques to help deal with it. Speak to your doctor or contact referral services such as Beyond Blue or Lifeline, which provide information and support to people with depression and anxiety. Improving your health and fitness by being more active and avoiding substances like alcohol and tobacco can also assist. And a healthier lifestyle will reduce your risk of cancer.

Fortunately, there’s no evidence that stress causes cancer – so it’s one less thing we need to worry about.
