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Breast cancer


What is breast cancer?

Breast cancer is the abnormal growth of the cells lining the breast ducts or lobules. These abnormal cells have the potential to spread to other parts of the body. Most breast cancers are invasive. This means the cancer has spread from the breast ducts or lobules into the surrounding breast tissue. Invasive breast cancer can be early, locally advanced or advanced (metastatic). Breast cancer is the most common cancer among Victorian females.

You can access further information about breast cancer, including risk factors, symptoms, diagnosis and treatment from Cancer Council Victoria. You can also call our trusted cancer nurses on 13 11 20 for support and to learn about our range of services for people affected by cancer.

The Victorian Cancer Registry also operates an interactive web portal, Data Explorer, which provides more trends and statistics than published here.

How common is breast cancer?

In 2020, 4608 Victorians were diagnosed with breast cancer. Of these, there were 33 males and 4575 females, representing 0.7% and 99.3% of the total Victorian breast cancer diagnoses, respectively. Currently, breast cancer is diagnosed at a rate of 0.6 per 100,000 males and 85.6 per 100,000 females. The median age at diagnosis of breast cancer is 69 years in males and 61 in females. Figure 1 and 2 show the distribution of breast cancer among Victorian females. Due to low numbers of cases when single years are displayed, Figure 1 and 2 do not include data for males. Accounting for 13.3% of all cancers diagnosed and 6.7% of all cancer-related deaths in 2020, breast cancer was the most commonly diagnosed cancer among females and the 32nd most commonly diagnosed cancer among males. It is the 2nd most common cause of cancer-related deaths in Victorian females and the 34th most common cause of cancer-related deaths in Victorian males.


Figure 1: Distribution of breast cancer incidence in 2020, by age groups

Source: Victorian Cancer Registry (2022)


Figure 2: Distribution of breast cancer incidence in females in 2020, compared to the distribution of the Victorian population in 2020, by 5-year age brackets

Source: Victorian Cancer Registry (2022)

Breast cancer morphology

Figure 4 provides a summary of the different types of cells (morphology) which have caused breast cancer for males and females combined. Most breast cancer tumours, 75%, present as Breast carcinoma, no special type.


Figure 4: Distribution of breast cancer morphologies between 2011-2020

Source: Victorian Cancer Registry (2022)


Breast cancer subtypes

A tissue biopsy of breast cancer tissue enables the molecular makeup of the tumour to be further examined. This is undertaken to determine the best treatment path. Some tumours may have cells with hormone receptors which help cancers to grow. Cancers which receive signals from oestrogen are referred to as oestrogen receptor positive (ER+) and those receiving progesterone signals are progesterone receptor positive (PR+) cancers. Breast cancer tissue is also examined to assess whether the presence of the protein human epithelial growth factor receptor 2 (HER2) that appears on the surface of the breast cancer cells and may stimulate cancer cells to grow. Breast cancer tissue with high levels of HER2 protein is referred to as HER2 positive (HER2+) or HER2 amplified.
Luminal tumours are hormone-positive (ER+ and/or PR+) and HER2 negative.
Non-luminal tumours are HER2+ but both ER and PR negative. Triple negative tumours refers to breast cancer tissue which does not contain oestrogen receptors, progresterone receptors or HER2 (TNBC). People diagnosed with TNBC are usually treated with chemotherapy, because the tumour does not respond to drugs specifically developed to target oestrogen or progesterone or HER2.
Figure 5 provides a summary of the hormone status of tumours diagnosed in 2020 among both males and females.


Figure 5: Distribution of breast cancer subtypes in 2020

Source: Victorian Cancer Registry (2022)

Geographical variance in breast cancer by local government area

Figure 6 demonstrates variation in age-standardised incidence rates of breast cancer, by local government areas. Darker shading indicates areas with higher rates of breast cancer.


Figure 6: Variation in the incidence of breast cancer for the period 2016-2020, by location of residence in Victoria

Source: Victorian Cancer Registry (2022)


Breast cancer in people born overseas

Figure 7 shows the age standardised incidence rates of breast cancers in Australian-born Victorians compared to other major migrant groups, over the five-year period 2016 to 2020. The highest age standardised incidence rate for breast cancers was 0.7 for males born in the Australia and New Zealand region and the lowest rate of 0.2 was observed in males born in the North-East Asia region. The highest age standardised incidence rate of breast cancers was 91.7 for females born in the Australia and New Zealand region and the lowest rate of 59.1 was observed in females born in the North-East Asia region.


Figure 7: Age standardised incidence rates and 95% confidence intervals for breast cancer in Victorians born in Australia compared to Victorians born in other countries for the period 2016-2020, by sex

Source: Victorian Cancer Registry (2022)


Source: Victorian Cancer Registry (2022)



Breast cancer distribution by stage at diagnosis

Figure 8 shows distribution of breast cancer by stage of disease at diagnosis in 2020. In females, Stage 1 accounted for the largest proportion (39.1%) of new diagnoses and Stage 4 accounted for the lowest proportion (4.6%) of new breast cancer diagnoses. Because of low numbers, data are not presented for males or those where sex is not recorded, or is recorded as indeterminate.


Figure 8: Breast cancer distribution by stage at diagnosis in 2020, females

Source: Victorian Cancer Registry (2022)


Breast cancer five-year relative survival

Figure 9 shows the change in 5-year survival for breast cancer among males and females, and the 5-year survival trend for all cancers over the same time period. It shows that 5-year relative survival has increased for breast cancer between 1985-1989 and 2015-2019 from 72% to 92%.

Figure 9: Trend in five year relative survival following diagnosis of breast cancer in five year brackets, from the period 1985-1989 to 2015-2019

Source: Victorian Cancer Registry (2022)

For further information relating to stage at diagnosis for breast cancer, please refer to:
https://www.cancervic.org.au/cancer-information/types-of-cancer/breast_cancer/diagnosing_breast_cancer.html

This webpage was last updated in May 2022