The link between inflammation and cancer was first suggested by Prussian physician Rudolf Virchow in 1863 after he found white blood cells – immune cells – in some cancerous tumours.
He thought that constant “irritation” caused by the immune system could be driving their development, and termed cancer “the wound that doesn’t heal” – not a bad way to describe chronic inflammation.
Scientists now understand that inflammation does play a multi-faceted role in certain cancers – not only as a primary cause, but also as a key component that helps tumours grow and even provides the means by which they spread throughout the body.
The inflammation that leads to cancer can be caused by chronic infection, inflammatory diseases or environmental factors that expose the body to harmful chemicals – this last factor could be the result of smoking, excessive drinking, poor diet or exposure to asbestos, for example.
A third of stomach cancer deaths are caused by infection with the bacterium Helicobacter pylori, which can set off a chronic inflammatory response. This is similar to the progression to cancer that can occur with fatty liver disease or viral infections of hepatitis B and hepatitis C, which can lead to inflammation of the liver that causes scarring, and can, in turn, result in liver cancer.
Researchers believe that some of the highly reactive molecules containing oxygen and nitrogen released during the inflammatory response are capable of causing DNA damage in cells, which, if not repaired, can play a role in the development of cancer.
The inflammatory response to a primary tumour is also now understood to help orchestrate the growth of cancer cells, as well as helping them spread – the devastating “metastasis” that can turn a treatable primary tumour into a terminal illness.
The inflammatory response sends out signals for immune cells to infiltrate the tumour. These produce proteins that, among other responses, muster forces to increase the blood supply carrying oxygen and nutrients to the affected region.
While this increased blood supply is designed to promote healing and recovery, it can have the opposite effect if the tumour hijacks the body’s own nutrient supply and drainage systems – the blood and lymphatic vessels respectively – to help spread the cancer cells to other organs.
“Many studies have implicated inflammation in the ability of a primary cancer to spread throughout our body,” says IMB’s Professor Matt Sweet.
Researchers now face the challenge of using our knowledge of inflammation to reduce the chance of cancer developing in the first place.
Liver cancer is now one of the fastest-growing causes of cancer death in Australia and has one of the poorest prognoses.
What about aspirin?
- Many studies have investigated whether an anti-inflammatory medication such as aspirin could reduce the risk of cancer but without any definite findings.
- Major lifestyle changes remains the best bet for risk reduction – stop smoking, lose weight, drink less, exercise more and eat well.
Cancer has been described as ‘the wound that does not heal’.
BY THE NUMBERS
One in two Australians will be diagnosed with cancer by age 85