Cancer is one of the most common public health threats facing Australians and accounts for nearly one-fifth of the disease burden in this country. The direct cost to the Australian community is approaching $4 billion per year.
Unless we do something now, this burden will increase. Rates of new cancers are expected to rise sharply over the next decade simply because our population is growing and ageing. This will place extra pressure on health-care management, support and follow-up services.
But there is hope. Despite their high burden, chronic diseases are the most preventable. Less than 10% of cancers are due to genetic or inherited disorders, meaning at least nine in ten cancers are due to external factors – many of which are not understood.
Fortunately, the impact of some of these risk factors is well known. In a recent international collaboration of scientific experts, the World Cancer Research Fund (WCRF) and American Institute for Cancer Research (AICR) estimated that 25% of cancers could be prevented if we eliminated poor nutrition and diet, physical inactivity and obesity.
Motivating populations to take action is very difficult and will require a concerted and significant effort – not only by the population themselves, but by governments and policy makers Australia wide. But such an effort is unlikely unless lifestyle change becomes a strong priority. First, we need some context.
In our paper, published in today’s Medical Journal of Australia, we tried to estimate what the impact of this 25% could be in 13 years, in 2025.
Of course, any projections are fraught with uncertainty, so we kept our calculations simple. We based our cancer predictions on population projections published by the Australian Bureau of Statistics. This is consistent with that used recently in a large study from the United States.
Using this method, we estimated that around 170,000 Australians could expect a cancer diagnosis in the year 2025 (up from 108,000 in 2007). This correlates with a recent Australian Institute of Health and Welfare estimate of 150,000 in 2020 .
One quarter of 170,000 equals about 43,000 people. So, if we can put steps in place to reduce poor diet, increase physical activity and reduce obesity, then potentially we could prevent the equivalent of the population of a city the size of Port Macquarie from being diagnosed with cancer in 2025. And not just in 2025, but every year after that.
It won’t be easy. Latest figures suggest the prevalence of sedentary behaviour, excess weight and obesity, and harmful alcohol consumption is generally increasing. Australians also have a culture of low consumption of fruit and vegetables. So, much needs to change.
Clearly, despite our efforts to improve lifestyles, people will still be diagnosed with cancer. So any prevention efforts need to be taken in conjunction with continued improvements in the detection and treatment of cancers.
But when you consider the costs of treatment, prevention offers substantial hope to reduce the burden of cancer using a sustainable method. And lifestyle-based cancer prevention can also reduce rates of other chronic diseases such as diabetes, hypertension, heart disease and stroke.
We know that for many people diagnosed with cancer, their prognosis depends on where they live. Areas with poor outcomes are also generally characterised by poorer diet, lower physical activity and high levels of obesity. A focus on prevention in these disadvantaged areas, and removing existing barriers to those prevention efforts, has the potential to reduce these current inequities in cancer outcomes.
Designing and implementing interventions in diet, nutrition, physical activity and obesity at a population level are not simple. Nor are they inexpensive. Even small changes at the individual level require a large amount of effort by governments. Interventions require long-term commitment, with results only evident 10 to 15 years later.
But given just over 2% of Australia’s total health expenditure in 2007-08 was spent on preventive services or health promotion, the potential is high.
If we are going to have any impact on reducing the significant human and financial burden of cancer in the future, governments and policy makers at all levels must act now.