Metastatic breast cancer - first national estimates

Each year, around 20,000 Australians (including around 200 men) are diagnosed with breast cancer and more than 3,300 (including around 30 men) die from it (AIHW 2025a).

Breast cancer is the most common cancer in Australian women (with about 1 in 7 women diagnosed in their lifetime, compared to 1 in 600 men) (AIHW 2025a).

The number of new cases of breast cancer is increasing at more than 2% per annum – largely a consequence of a growing population of women and ageing of the population. If ageing of the population is taken into consideration, the rate of diagnosis of new cases of breast cancer increased from 81 cases per 100,000 women in 1982 to 128 per 100,000 in 2014 and then remained relatively steady to 2021 (123 per 100,000), and is projected to be 121 per 100,000 in 2025 (AIHW 2025a).

The 5-year relative survival rate for people diagnosed with breast cancer increased from 75% in 1987–1991 to 93% in 2017–2021 (AIHW 2025a). Five-year relative survival is the percentage of people diagnosed with a cancer who survived for at least 5 years after diagnosis, relative to people of the same age and sex in the population. Five-year observed survival for breast cancer was 67.6% in 1987–1991 and was 86.5% in 2017–2021. Five-year observed survival is the percentage of people diagnosed with breast cancer who survived for at least 5 years after diagnosis; it should be noted for observed survival that a person diagnosed with cancer may have a cause of death other than cancer.

While survival rates for breast cancer overall are high, there is substantial variation in survival by stage at diagnosis. For example, 5-year relative survival in 2011 (the most recent period for which national stage data was available) was 100% for stage I compared to 32% for stage IV (metastatic) (AIHW 2021a).

Largely as a result of improvements in survival for breast cancer (due to earlier detection and improvements in treatment over time), the death rate due to breast cancer has decreased from 38 deaths per 100,000 women in 1984 to a projected 21 deaths per 100,000 women in 2025 (AIHW 2025a), while the absolute number of deaths has increased from just over 2,000 deaths in 1984, to just over 3,300 deaths projected for 2025 (AIHW 2025a).

In this report, all deaths attributable to breast cancer are assumed to be deaths due to metastatic breast cancer. However, it is possible for deaths to be caused by breast cancers that are not metastatic, but this is relatively rare (Palmieri et al 2022).

Risk factors for breast cancer

Risk factors for breast cancer include older age, reproductive or hormonal factors such as not having carried or given birth to any children (or to fewer children), older age at birth of first child, younger age at menarche, and older age at menopause, a family history of breast cancer and other risk factors such as higher body mass index, exposure to X-rays and gamma radiation, tobacco use and consumption of alcoholic beverages (AIHW 2024, AIHW 2025b).

The only factor known to be protective against breast cancer is breastfeeding.

The importance of screening

BreastScreen Australia provides free 2-yearly screening mammograms to women aged 40 and over and actively targets women aged 50–74. Just over half of women in the target group have participated in the most recent 2 years.

Demonstrating the benefit of screening for breast cancer, a recent study (AIHW 2021b) found that 60% of breast cancers detected through BreastScreen Australia were small, compared with 30% for unscreened women. The same study also reported that breast cancers diagnosed through BreastScreen Australia were found to have more than 50% lower risk of causing death than those diagnosed in women who had never screened.

Metastatic breast cancer

Metastatic breast cancer is breast cancer that has spread from the breast (and nearby lymph nodes) to other parts of the body. It is also referred to as advanced, stage IV, or secondary breast cancer.

Common sites of spread include the bones, liver, lungs, and brain. Metastatic breast cancer can arise months or years after a person’s initial early-stage breast cancer diagnosis or, in some cases, be the first diagnosis if the cancer was already advanced when detected.

Metastatic breast cancer is currently incurable and is managed as a life-limiting condition requiring ongoing treatment.

While the number of people affected by breast cancer is known and well supported by good data, the same is not yet true for metastatic breast cancer.

See Cancer Australia for more information on metastatic breast cancer.