Complex modelling research informs national cancer strategies

Where you live could have important implication on your chance of developing cancer and surviving the disease, according to pioneering research at ACEMS.

Dr Susanna Cramb, a former ACEMS PhD student and now an ACEMS Associate Investigator who is currently with Cancer Council Queensland, is investigating small-area differences in cancer incidence, survival and screening in Queensland and across the country.

These unique insights are informing preventive health programmes and cancer treatment services in Australia and Susanna’s modelling approach
has been adopted internationally. Such breakthroughs are sorely needed as an alarming one in two Australian men and women will be diagnosed with cancer by the age of 85. In 2013, cancer was ranked the leading cause of death in the country.

“In Australia alone, more than 134,000 Australians are diagnosed with cancer each year,” says Susanna. “This disease has a huge impact on people and the economy, but because cancer is one of the few diseases with almost complete incidence data available, there is a unique opportunity to use routinely collected data to gain understanding of the disease.

“There is some evidence that cancer incidence and outcomes may differ based on where you live. Often people living in either more remote or socioeconomically disadvantaged areas tend to have worse outcomes from cancer.

“Yet small-area differences in cancer incidence, survival and screening have never been examined comprehensively across the country. We need to know where cancer patients are experiencing less than optimal outcomes.”

Susanna’s Queensland study was an eye opener – it confirmed that where you live can affect your risk of being diagnosed with or surviving cancer. For example, it showed that if you are diagnosed with localised breast cancer, regardless of where you live in Queensland, you have a very high survival rate. However, for advanced breast cancers, there is much poorer survival among more remote areas. In contrast, bowel cancer often has lower survival in more remote areas regardless of the cancer stage at diagnosis.

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The underlying areas used are Statistical Areas Level 2 (SA2s). These maps of excess hazard ratios (EHRs) represent the risk of dying from breast cancer within 5 years in comparison to: 1) the Queensland average in 1997-2004 (for both 1997-2004 and 2005- 2012) and 2) in comparison to each individual SA2 (“Changes over time”), so 1 = the same EHR in that SA2 during 1997–2004. SA2s aim to represent a community that interacts together socially and economically; there are 526 SA2s covering all of Queensland without gaps or overlaps.

The study, ‘Spatial variation in cancer incidence and survival over time across Queensland, Australia’, published in 2017, examined the space-time differences in cancer incidence and survival for the five most common cancers (bowel, melanoma, lung, breast, prostate), diagnosed during 1997-2004 and 2005-2012, across 516 small areas in Queensland.

The researchers concluded that there were enduring variations in cancer incidence and survival across small-areas in Queensland, requiring further research to understand the reasons behind the disparities. The work builds on several studies, including the ‘Queensland Atlas of Cancer’ published in 2011, that examined small-area cancer disparities using spatial modelling.

These findings are being used by government agencies, health policy makers, and non-government organisations to inform state and local planning policies and underpin preventive health programmes and cancer treatment services. In addition, the work feeds into strategic objectives designed to reduce variations in cancer indicators in Queensland between metropolitan, regional and rural areas, as well as among socio-economic groups.

The Queensland Atlas has been instrumental in achieving a doubling of Queensland Health’s Patient Travel Subsidy Scheme, and a State Government commitment of $100 million in additional funding over four years, improving access to health services for regional patients. The research has also led to placement of additional Cancer Council Queensland staff positions in regional areas to assist in supporting and providing information to rural/remote cancer patients.

From a knowledge perspective, these studies have improved understanding of at-risk populations and strengthened the evidence-base available to public health advocates. They have also laid a path for future research into geographic disparities and survival trends. Methods utilised in the study have been adopted internationally by those such as the Institute of Cancer Epidemiology, Lubeck, which has produced the small-area Cancer Atlas Schleswig-Holstein, Germany.

Susanna’s next project, in collaboration with ACEMS Deputy Director and Chief Investigator Distinguished Professor Kerrie Mengersen, and ACEMS researchers Jessie Roberts and Dr Earl Duncan, is to create a National Cancer Atlas for Australia. The study is supported by Cancer Council Queensland, Queensland University of Technology, the Australian Institute of Health and Welfare, and Australia and New Zealand Cooperative Research Centre for Spatial Information.

The project will investigate small-area differences in cancer incidence, survival and screening across the country to pinpoint where cancer patients are experiencing less than optimal outcomes. The Atlas, available online from July 2018, will enable users to understand the patterns in cancer incidence and survival for more than 20 types of cancer, as well as screening for bowel, breast, cervical and prostate cancers. Underpinning the estimates will be complex statistical models. Such statistics are vital in identifying those at greatest risk, monitoring the success of existing cancer strategies and developing adequate services.

“No-one can fight an invisible foe,” explains Susanna. “Statistics are used to illuminate and monitor cancer: to see whether mortality is decreasing, survival is improving, to plan for where services are needed, and understand what ages are affected. Our focus is on monitoring cancer at the small-area level.”

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