Metastatic breast cancer - first national estimates

No systematic nationwide recording of progression to metastatic stage

In Australia, registration of all primary cancer diagnoses is virtually complete. This is because cancer is a notifiable disease in all states and territories in Australia, and all cases are notified to the relevant state or territory cancer registry, which then forward details to the Australian Cancer Database (ACD) at the AIHW.

However, currently there is no national (or jurisdictional) means of systematically recording when a cancer has progressed to the metastatic stage. The fact of progression would need to rely on notification by various providers such as pathology laboratories, imaging clinics and hospitals. The exact number of women who are living with MBC therefore remains unknown.

The current lack of accurate data on how many women are living with MBC and their demographic characteristics, limits the ability of governments and health services to design supportive policy and programs, and to plan for workforce needs, service delivery or resource allocation.

Improving cancer data in Australia

Cancer stage and recurrence data are essential for understanding disease progression and planning treatment. However, these data are complex to collect because they are not available from a single source and require linkage of a wide range of data across pathology, radiology, hospital and clinical systems.

Australian Cancer Data Alliance

The AIHW established the Australian Cancer Data Alliance (ACDA) to provide national leadership and expert advice on improving cancer data. The ACDA is working to coordinate efforts across jurisdictions, develop innovative estimation methods and support capability building in state and territory cancer registries. The aim of the ACDA is to engage relevant stakeholders across the cancer sector to provide leadership and expert advice to develop a sustainable and fit-for-purpose data system and ensure consistent cancer data collection across the cancer data ecosystem. One of the priorities of the ACDA is to work with clinicians and registries to address the complicated issue of metastasis data for various cancers, starting with breast cancer.

The AIHW also established a Metastatic Breast Cancer Prevalence Working Group, as a subgroup of the ACDA, to enable broader consultation on methodologies, barriers and enablers to develop national data on people living with metastatic cancer. The AIHW has collaborated with this Working Group to expand on the work undertaken by several states and developed candidate methods for producing initial national estimates of metastatic breast cancer prevalence using currently available national data.

How this project has contributed

This is the first national estimate of metastatic breast cancer prevalence using available national data.

Contributors and funding

This work was made possible by Australian Government funding to improve the collection of data on metastatic cancer in Australia.

This work builds on the Australian Cancer Plan and responds to Breast Cancer Network Australia’s (BCNA) roundtable and report Time to Count People with Metastatic Breast Cancer: A Way Forward (BCNA 2023). The BCNA has played a vital role by ensuring consumer voices are central to this work, advocating for data improvements that reflect real-world needs.

The Cancer Institute New South Wales (CINSW), Cancer Council Victoria (CCV) and Cancer Alliance Queensland (CAQ) provided expert advice and shared jurisdictional experience to inform national estimates of metastatic breast cancer prevalence. Their collaboration has been essential for testing candidate methods and identifying practical solutions for data collection.

The Australasian Association of Cancer Registries (AACR) has also contributed through their engagement and supporting technical discussions.

Building national integrated data capacity

Australia needs a strategic, nationally integrated cancer data system to maximise public benefit. Current arrangements are fragmented, leading to inefficiencies and limiting the availability and quality of cancer data to inform public policy.

The AIHW is working in collaboration with state and territory cancer registries; members of the ACDA; the Department of Health, Disability and Ageing; and Cancer Australia, to address these needs and accelerate progress under Strategic Objective 2 ‘A sustainable and fit-for-purpose data system’ of the National Cancer Data Framework. Advancing the collection of cancer stage at diagnosis is one of the priority actions under this strategic objective – cancer stage is important for exploring variations in outcomes across population groups, evaluating treatment appropriateness, and assessing the success of screening and early diagnosis initiatives (Cancer Australia 2025). Improving national cancer stage data requires the linkage of multiple datasets across the fragmented and complex cancer data ecosystem. Initial linkages of New South Wales and Western Australian cancer registry data with the AIHW’s National Health Data Hub are scheduled to begin in November 2025.

Phase 2 of the work to produce national estimates of metastatic breast cancer prevalence will refine the estimates in this report through the use of these soon to be available linked data. The planned linkage of cancer data to the National Health Data Hub (NHDH) will strengthen this capacity by enabling more complete and reliable estimates.

These initiatives support the Australian Cancer Plan and the National Cancer Data Framework, which aim to deliver timely, comprehensive and integrated cancer data for policy, research and clinical care.