National Guide

Chapter 19 | Cancer prevention and early detection

Breast cancer







National Guide to preventive healthcare for Aboriginal and <br/>Torres Strait Islander people
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      3. Breast cancer

Cancer | Breast cancer

Dr Sarah Cush 

Key messages

  • Breast cancer remains the most common cancer diagnosed in Aboriginal and Torres Strait Islander women.1
  • Healthy weight, maintaining physical activity and avoiding harmful alcohol intake and tobacco smoking reduce the risk of breast cancer.2
  • Aboriginal and Torres Strait Islander women aged 50–74 years at population risk are recommended to have a screening mammogram every two years.3
  • Aboriginal and Torres Strait Islander women more frequently present at later stages of disease.3
Type of preventive activity - Screening
Who/target population What When Strength of recommendation Key source(s) and reference(s) Rationale/key considerations informing recommendation
All adult women Ask about risk factors for breast cancer

Consider using the iPrevent tool (see Useful resources) 		 Opportunistically Strong Australian report4 If high-risk women can be identified early, they can be given more options for prevention and early detection
All adult women Discuss breast awareness, rather than promoting regular breast self-examination Opportunistically Conditional Position statement5
International guideline6		 Does not change the stage of breast cancer at presentation or reduce mortality
All adult women Investigate new breast lumps with the ‘triple test’:
  • history and examination
  • imaging
  • biopsy
(See  Useful resources)		 As clinically indicated Strong National guideline7 The triple test can detect over 99.6% of breast cancers
Women at population risk aged under 40 years Do not screen N/A Conditional Position statement5 Harm outweighs benefit
Women at population risk aged 40–49 years Do not routinely recommend screening mammography; however, it is available and funded via BreastScreen every two years when requested

In some jurisdictions, women are being encouraged to commence screening from age 40 years		 Every two years when requested Conditional Position statement5
International guideline6		 Shared decision making is encouraged; in this age group, benefit may not outweigh harm for an individual
Women at population risk aged 50–74 years Recommend screening mammography Every two years Conditional Position statement5 Benefit likely to outweigh risk in underscreened population
Increased uptake in screening is supported by partnerships with Aboriginal and Torres Strait Islander Community Controlled Health Organisations (ACCHOs)
Women at moderately increased risk (ie 1.5- to 3-fold the population risk) aged under 40 years Do not screen N/A Conditional Position statement5 Harm outweighs benefit
Women at moderately increased  risk (ie 1.5- to 3-fold the population risk) aged 40–74 years Recommend screening mammography Annually may be recommended Conditional Position statement5 Benefit likely to outweigh risk
Women at high risk (ie more than threefold the population risk) Advise referral to a family cancer clinic or specialist cancer clinic, where available, for further assessment of risk and advice about genetic testing, screening and prevention When noted as high risk Strong International individual study8 Women at high risk of breast cancer should be given screening and surveillance options in a multidisciplinary clinic
Type of preventive activity - Behavioural
Who/target population What When Strength of recommendation Key source(s) and reference(s) Rationale/key considerations informing recommendation
All adult women Provide healthy living behavioural risk factor counselling on the benefits of regular physical activity, maintaining healthy weight, safe alcohol intake, avoiding smoking (refer to Chapter 2: Healthy living and health risks) Opportunistically Strong Systematic review9 Primary prevention of breast cancer
Pregnant and breastfeeding women Advise that breastfeeding has been shown to reduce the risk of breast cancer, and support women to breastfeed their infants (refer to Chapter 6: Child health) During and after pregnancy Conditional Systematic review and meta-analysis10–12 Primary prevention of breast cancer
Women considering combined menopausal hormone treatment (MHT) Advise about risks and benefits of combined MHT

In particular, advise about the increased risk of breast cancer with continuous use for more than five years		 When considering commencing MHT and every six months for women on combined MHT Conditional International case control studies13 Advice needs to be tailored for each woman
Type of preventive activity - Medication
Who/target population What When Strength of recommendation Key source(s) and reference(s) Rationale/key considerations informing recommendation
Women identified as being at high risk, and women aged over 35 years at moderate risk Consider specialist referral to discuss preventive treatment with tamoxifen or raloxifene as indicated by menopausal status When required when calculated to be at potentially high risk Strong Systematic review14
Position statement15		 Women at high risk should be given all options to reduce their risk, in a multidisciplinary setting
  • Use organised client reminder and recall systems, culturally appropriate resources for participants and collaboration with BreastScreen, including the use of mobile screening units, and arranging transport for women living remotely to attend services to support participation in screening.
  • Participation in mammographic screening may be improved with health promotion campaigns through ACCHOs.

General

Tools

Background

Breast cancer remains the most common cancer diagnosed in Aboriginal and Torres Strait Islander women.1 The incidence of breast cancer in Aboriginal and Torres Strait Islander women aged 50–74 years is 284 per 100,000 women, compared with 314 per 100,000 in non-Indigenous Australian women.16 Early detection through screening and improved treatment options have decreased overall breast cancer mortality from 74 to 50 deaths per 100,000 women in this age group between 1991 and 2010,16 yet Aboriginal and Torres Strait Islander women are still 1.2-fold more likely to die from the disease.17

Aboriginal and Torres Strait Islander women have lower participation rates in mammographic screening programs. The estimated participation rate of self-identified Aboriginal and Torres Strait Islander women in BreastScreen for the target age group was 41% in 2019, compared with 54% for non-Indigenous Australian women.17 Consequently, Aboriginal and Torres Strait Islander women are more likely to be diagnosed at an advanced stage.5 Barriers for breast cancer screening include cultural safety and geographic remoteness, with participation rates increasing when there are community-led partnerships between ACCHOs and BreastScreen.1 Although a more aggressive tumour type has been identified among Aboriginal and Torres Strait Islander women in the Northern Territory (a human epidermal growth factor receptor 2 [HER2]-enriched phenotype),16 it is considered that this plays a minimal role in the overall disparity of survival when lower rates of screening, later stage at diagnosis and lower completion rates of chemotherapy are factored in.18

Breast cancer in men is outside the scope of this topic, except to note that if a man notices any changes in breast tissue, they should be investigated.

The term ‘woman’ in this guideline refers to all who identify as such. Specific recommendations for the transgender community are beyond the scope of this guideline. Although transgender women have a lower risk than cisgender women, their risk can be influenced by gender-affirming hormones, and although transgender men have an increased risk compared with cisgender men, their risk can be decreased by gender-affirming surgery and hormones.19 All individuals are encouraged to speak with their healthcare provider to discuss their risk and options. BreastScreen offers mammograms to all eligible clients in an inclusive way. Further information is available from BreastScreen NSW, with recommendations for screening,20 and BreastScreen Victoria has developed resources to improve the access for the transgender and gender-diverse community.4

There are known risk factors that can be modified to reduce a woman’s risk of developing breast cancer and known risk factors that can help identify women at higher risk of developing breast cancer. Understanding and individualising risk enables additional, tailored preventive activities for women at higher risk.

Behavioural

Healthy behaviours that can reduce the risk of breast cancer include regular moderate exercise, healthy weight (particularly after menopause), not smoking/smoking cessation and the safe use of alcohol.9 Breastfeeding reduces the risk of triple-negative breast cancer by 20% and by 22–55% in carriers of BRCA1 gene mutations.21 Furthermore, prolonged breast feeding of infants reduces the risk of breast cancer by 4.3% for every 12 months of breast feeding.10,11,21

Screening for estimated risk

Women should be screened for their level of risk, particularly to identify women at moderate and higher risk so that an individualised approach for additional risk reduction activities can be developed. iPrevent is a breast cancer risk assessment and management tool designed to identify women at higher risk and guide preventive activities based on this identified risk.22,23 It uses family history and personal factors, including age of menarche and menopause, medication use and body mass index.22 The iPrevent tool uses algorithms based on data from women with European ancestry only and does not account for differences in breast cancer incidence among different ethnicities.24 There is limited information on genetic breast cancer risk in Aboriginal and Torres Strait Islander women.25 Although more research and validation are needed to improve the accuracy of the iPrevent tool for Aboriginal and Torres Strait Islander women, it is still suitable to inform discussions on known risk factors.4 In an Australian study in general practice settings, the iPrevent tool was shown to have good usability, without increasing women’s anxiety.26

Screening

Mammographic screening has been shown to reduce mortality and is recommended for all women of average population risk aged between 50 and 74 years.5 Although mammographic screening is also funded for women aged between 40 and 49 years, there is a much smaller benefit to risk ratio in this age group because there is a high false positive rate that can lead to overinvestigation and unnecessary anxiety.6

Although Aboriginal and Torres Strait Islander women are diagnosed with breast cancer at a younger age, the relative risk of being diagnosed younger was not higher than among non-Indigenous Australian women, so there is no current evidence or consensus for Aboriginal and Torres Strait Islander women to start screening at a younger age.27

Improving breast cancer screening in Aboriginal and Torres Strait Islander women through culturally safe access to mammography should be actively promoted to reduce the risk of death from breast cancer.28 Interventions that are community led are more effective in increasing participation in breast screening.18 An example of a community-led project that is effective in increasing participation in screening is The Beautiful Shawl Project.29 In this project, women are invited to a mobile BreastScreen unit and are provided with a shawl designed by an artist from their community. The shawl has been designed for women to wear during the mammogram. Women have said it empowers them by connecting them to Country and the protection of their ancestors. In addition, the staff of the BreastScreen units have all undergone cultural training (see The Beautiful Shawl Project in Useful resources). Mobile BreastScreen units and transport provided by community health services are also tools used throughout Australia to increase participation in screening. Participation in mammographic screening may also be improved by recall and reminder systems and by having community members facilitating community-based events.17 These strategies are discussed in further detail in Breast cancer: A handbook for Aboriginal and Torres Strait Islander health workers and health practitioners.30

Regular breast examination is no longer recommended, but breast awareness is encouraged.6 Any changes noticed in breast tissue should be reviewed and investigated appropriately.7

Women identified as being at higher risk

For women identified as being at higher-than-average risk, referral to a multidisciplinary specialist service with the capacity to offer genetic counselling and testing, chemoprophylaxis and risk-reducing surgery, as appropriate to the risk and preference of each individual woman, is recommended.

Risk reduction medications (chemoprophylaxis) are effective in reducing the risk of oestrogen receptor-positive breast cancer in high-risk women. These medications include the selective oestrogen receptor modulators tamoxifen and raloxifene, as well as the aromatase inhibitors anastrozole or exemestane, depending on menopausal status. Tamoxifen is the most effective option for premenopausal woman, and treatment with 20 mg daily over five years can reduce a women’s risk for 20 years.31 There are significant side effects to each of these medications, and the benefits and side effects must be weighed up individually. It is important to note that these risk-reducing medications should not be used for more than five years.14,15

Risk-reducing surgery, such as prophylactic oophorectomy or mastectomy, may be an option for very high-risk women, such as carriers of BRCA gene mutations.8,32

Women at high risk should be encouraged to observe the healthy living behaviours that support prevention and continue to undergo mammographic screening. The frequency of the screening may increase depending on the increased risk.

Menopausal hormone therapy

MHT (formerly known as hormone replacement therapy), is the most effective treatment option for women experiencing menopausal symptoms interfering with quality of life.33 When the first results of the Women’s Health Initiative Study was released in 2002, an alarm was raised of a connection between MHT and breast cancer.34 There has since been a reanalysis of the data, and further studies have clarified that the risks of MHT depend on multiple factors, including age, comorbidities, time since menopause and the dose, duration and form of MHT used.34,35 Overall, for women aged younger than 60 years or within 10 years of menopause, the quality of life and cardiovascular benefits of MHT seem to outweigh the risk of breast cancer for most.36 Specifically, oestrogen-only MHT increased the risk of breast cancer by three extra cases per 10,000 women-years, whereas combined oestrogen/progesterone MHT close to the menopause for less than five years increased breast cancer risk by nine extra cases for 10,000 women-years.35 After discontinuation, this increased risk does decline, but it remains raised for many years13(see Table 1).

The clinician toolkits from Jean Hailes and Monash University are Useful resourcess to help clinicians discuss the benefits and risks, as well as suitable MHT options, with women (see Useful resources).

 
 Table 1. Number of extra cases of breast cancer per 10,000 women-years for women exposed to menopausal hormone therapy versus unexposed women
   Age group (years)
  50–59 60–69 70–79
Oestrogen only   
Recent use 1–5 years 3 4 8
Recent use ≥5 years – 5 8
Oestrogen+progestogen   
Past use 1–5 years – 2 5
Past use ≥5 years – 5 8
Recent use 1–5 years 9 15 19
Recent use ≥5 years 15 29 36
Table reproduced from the Australasian Menopause Society,35 with original data from Vonogradova.13
 
 
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