More than one-third of cancers can be avoided if Australians modify their lifestyle

Nearly 40,000 cancers diagnosed in Australia can be reduced if people avoid known risk factors for the disease, according to research published today.

In 2010, 116,850 Australians were diagnosed with invasive cancer. The new study identifies 13 areas where people can alter their lifestyle to prevent a third of these.

Led by clinicians at the QIMR Berghofer Medical Research Institute, researchers applied international measurements to calculate Australian data.

Published today in the Australian and New Zealand Journal of Public Health, the study showed smoking, ultraviolet radiation, body weight, diet, and alcohol, contributed to 90% of all preventable cancers.

Modifiable risks accounting for the remaining 10% of cancers were:

• Red and processed meat
• Inadequate fibre intake
• Inadequate intake of vegetables
• Inadequate intake of fruit
• Inadequate physical activity
• Infections such as hepatitis B and C, human papilloma virus, Helicobacter pylori bacterium, HIV and Epstein-Barr Virus.
• Hormone replacement therapy (HRT)
• Oral contraceptives
• Inadequate breast feeding.

Director of the Sansom Institute for Health Research, Ian Olver, said the often convoluted reports about causes of cancer distracted people.

“People think, ‘oh everything causes cancer, I don’t need to be worried about it’. But this study actually refocuses it on the things that can prevent about a third of them - and it’s simple lifestyle changes,” he said.

Risk factors considered for the report had to meet three conditions: be classified by the World Health Organization or the World Cancer Research Fund as a cause of at least one cancer type; be modifiable; and there had to be reliable data on numbers of Australians exposed to the particular risk.

Associate Professor in Nutrition at Deakin University, Tim Crowe, said while the research was significant in its credibility, there was no magic formula it exposed to avoiding cancer.

“It’s about eating plenty of plant-based foods and fibre, being active, not drinking too much and trying to maintain as healthy a body weight as possible,” he said.

“You could apply those recommendations to reducing the risk of diabetes and heart disease. It’s a common theme across many chronic diseases.”

The study suggests nearly 2,000 cancer cases diagnosed in Australia in 2010 were attributable to inadequate intakes of fruit and vegetables.

Low levels of dietary fibre were responsible for at least 1,000 – and possibly up to 2,600 – bowel cancers.

Professor Sanchia Aranda, chief executive officer of Cancer Council Australia, which commissioned the study, said bowel cancer was a major issue in the country.

“We have a particularly low participation in our national bowel screening program in Australia. Our target is 70% of the target population and we’re sitting at about 33% at the moment,” she said.

The report showed red and processed meat were significant risk factors for bowel cancer, accounting for about 17% of all such new diagnoses in 2010.

It states if Australian adults consumed less than 65 grams of red and processed meat per day, around 800 fewer cases of bowel cancer would have been diagnosed in 2010.

Professor Aranda said Australia’s culture of barbecues with a high red meat component contributed to it sharing the highest level of bowel cancer in the world with New Zealand.

She also said there was a worrying rise in rates of liver cancer in Australia.

The study showed the hepatitis virus contributed to around 30% of liver cancer diagnoses. But alcohol and tobacco were responsible for 13% and 21% respectively.

“It’s always been thought the rising rates of liver cancer was largely due to infections.

“But in France, recent reports suggest that about 50% of their liver cancer is due to drinking too much alcohol,” Professor Aranda said.

Hormone replacement therapy (HRT) for menopausal women was found to be both a risk and protective factor, depending on the type of cancer.

The study suggested more than 500 Australian women – and perhaps as many as 675 – developed cancer in 2010 as a consequence of using HRT. But nearly 90 cancers were prevented when women used the therapy.

Professor Olver said the information was complicated and women using HRT who were worried about their cancer risk should consult with their doctor.

Women most at risk of cancer are those using the therapy for longer than five years.

“There are a lot of factors that have to be balanced. If you’re having dreadful symptoms from being post-menopausal, then you need to do something about them because it ruins your quality of life,” Professor Olver said.

“This is something individual patients have got to talk to their doctors about; their individual situations and risk factors and reasons for needing to be on or not be on HRT.”

Overall, the study showed tobacco smoke to be the only risk factor with no safe level of intake, while there was no limit to recommended levels of fruit and vegetable consumption.

“The interesting thing about this is that it’s not saying to cut out anything,” said Tim Crowe.

“It’s really about having more of. More of plant-based foods, and not going overboard on eating red meat.”