STEP 1: Prevention and early detection

This step outlines recommendations for the prevention and early detection of breast cancer.

Evidence shows that not smoking, avoiding or limiting alcohol intake, eating a healthy diet, maintaining a healthy body weight, being physically active, being sun smart and avoiding exposure to oncoviruses or carcinogens may help reduce most cancer risk (Cancer Council Australia 2018).

These are the convincing risk factors for developing breast cancer (Cancer Australia 2018) (those highlighted in bold are modifiable):

  • age
  • gender (being female)
  • significant family history of breast cancer and/or other cancers
  • pathogenic variants in cancer predisposition genes including BRCA1, BRCA2, CDH1, PALB2, PTEN, NF1, STK11, TP53, ATM and CHEK2
  • DCIS (ductal carcinoma in situ)
  • LCIS (lobular carcinoma in situ) also referred to as non-invasive lobular neoplasia
  • atypical epithelial proliferative lesions (atypical ductal hyperplasia and atypical lobular hyperplasia)
  • previous breast cancer
  • high mammographic breast density (must be adjusted for age and body mass index)
  • early menarche
  • not bearing children
  • never having breastfed
  • late age at first birth
  • late menopause
  • maternal exposure to diethylstilboestrol (DES) in utero
  • use of combined hormone replacement therapy, particularly for extended periods over many years
  • not engaging in adequate physically active
  • overweight and obesity (only for postmenopausal women)
  • weight gain (postmenopausal)
  • alcohol consumption
  • exposure of the breast to ionising radiation.

For more information, visit the Cancer Australia breast cancer risk factor website.

Recommendations that may assist in preventing breast cancer include:

  • maintaining a healthy weight
  • avoiding or limiting alcohol intake to no more than 10 standard drinks a week and no more than four standard drinks on any one day
  • getting 30 minutes or more of moderate-intensity (puffing) exercise most days (150–300 minutes per week)
  • avoiding or limiting hormone replacement therapy use
  • additional prevention strategies in people with increased risk (e.g. gene mutation carriers).

Additional prevention interventions are considered for women at increased risk, including those at moderately increased risk. For example, those at moderately increased risk (1.5–3 times the population risk) may be offered medication to reduce risk, and those at high risk (more than three times the population risk) may be offered medication or risk-reducing surgery.

Everyone should be encouraged to reduce their modifiable risk factors (see section 1.1).

For women assessed as having an increased risk of breast cancer, antihormonal risk-reducing medication such as tamoxifen, raloxifene or an aromatase inhibitor is an option to lower the risk of developing breast cancer. Decisions about whether to use risk-reducing medication should be based on an accurate risk assessment and clear understanding of the absolute benefits and risks for each individual woman. The benefits and risks for an individual can be assessed by using iPrevent.

Risk-reducing surgery such as prophylactic bilateral mastectomy may be considered by women at high risk of developing breast cancer (NCI 2015), including those with a mutation in a major breast cancer predisposition gene such as BRCA1 or BRCA2 (Cancer Council Australia 2015).

Bilateral risk-reducing mastectomy reduces the absolute risk of breast cancer by at least 90 per cent (NCI 2015). Even with total mastectomy, not all breast tissue can be removed. The remaining breast tissue may be at risk of becoming cancerous in the future (NCI 2013).

Knowledge of a woman’s risk factors can be used to objectively assess her individual breast cancer risk using a validated tool such as iPrevent.

By accurately assessing a woman’s personal breast cancer risk level, health professionals can offer the most appropriate evidence-based prevention and early detection strategies. All women should therefore consider having their individual breast cancer risk assessed. This can be done by women themselves or in primary care. Cancer risk assessment should be repeated when major risk factors change (e.g. new family cancer history, breast biopsy showing atypical hyperplasia or LCIS).

There are a number of validated computerised breast cancer risk assessment tools that estimate a woman’s breast cancer risk based on her individual risk factors:

iPrevent is an Australian tool designed for self-administration by women and collaborative use with clinicians and is the only tool that links the risk assessment directly to the relevant risk management guidelines.

In Australia, absolute lifetime population risk of breast cancer is 12 per cent, but most women are below this risk. Cancer Australia defines levels of breast cancer risk as follows:

  • average risk: < 1.5 × population risk
  • moderate risk: 1.5–3 × population risk
  • high risk: > 3 × population risk (Cancer Australia 2010).

People with or without a personal history of breast cancer at high risk due to their family cancer history should be referred to a familial cancer service for further risk assessment and for possible genetic testing (eviQ 2019a). Consider referring:

  • untested adult blood relatives of a person with a known pathogenic variant (mutation) in a breast and/or ovarian cancer predisposition gene (e.g. BRCA1 or BRCA2, TP53, PTEN, STK11, PALB2, CDH1, NF1) or
  • people with two first- or second-degree relatives diagnosed with breast or ovarian cancer plus one or more of the following on the same side of the family:
  • additional relative(s) with breast or ovarian cancer
  • breast cancer diagnosed under age 50 years
  • more than one primary breast cancer in the same woman
  • breast and ovarian cancer in the same woman
  • Jewish ancestry
  • breast cancer in a male
  • pancreatic cancer
  • high-grade (≥ Gleason 7) prostate cancer.

Additionally, people with breast cancer should be referred to a familial cancer service if they meet the following criteria:

  • male breast cancer at any age
  • breast cancer and Jewish ancestry
  • two primary breast cancers in the same person, where the first occurred under age 60 years
  • two or more different but associated cancers in the same person at any age (e.g. breast and ovarian cancer)
  • breast cancer aged under 40 years or triple-negative breast cancer aged under 50 years
  • lobular breast cancer and a family history of lobular breast or diffuse-type gastric cancer
  • breast cancer aged under 50 years with limited family structure or knowledge (e.g. adopted)
  • breast cancer and a personal or family history suggestive of:
  • Peutz-Jegher syndrome (oral pigmentation and/or gastrointestinal polyposis)
  • PTEN hamartoma syndrome (macrocephaly, specific mucocutaneous lesions, endometrial or thyroid cancer)
  • Li-Fraumeni syndrome (breast cancer < 50 years, adrenocorticocarcinoma, sarcoma, brain tumours).

Referral can also be considered if finding a relevant germline mutation would have high clinical utility (e.g. would alter treatment of the current cancer).

Asymptomatic women

A significant proportion of breast cancers are diagnosed through mammographic screening in women who are asymptomatic. Assess a woman’s individualised risk to see whether a personalised screening regimen may be appropriate.

Early detection through screening mammography has several benefits including improved mortality rates, increased treatment options and improved quality of life (Cancer Australia 2015a). For women with small tumours at diagnosis (< 10 mm), there is a more than 95 per cent five-year survival rate (Cancer Australia 2012).

BreastScreen Australia services operate within the framework of a comprehensive set of national accreditation standards that specify requirements for the safety and quality of diagnostic tests, timeliness of services and multidisciplinary care.

State, territory and federally funded two-yearly mammographic screening is offered to asymptomatic women from the age of 50 to 74 years through the BreastScreen Australia program (although available after 40 years of age upon request).

A doctor’s referral is not required for screening through BreastScreen Australia, but general practitioners’ encouragement is a key factor in women’s participation in screening.

Not all breast cancers are detectable on screening mammograms, and new cancers may arise in the interval between mammograms. Women should be aware of the look and feel of their breasts and report concerns to their general practitioner.

Women invited to screening should be provided with information about the risk and benefits of mammographic screening.

There is a 42 per cent reduction in risk of dying from breast cancer in screened women (AIHW 2018b) and a significant reduction in treatment intensity for patients diagnosed within a screening program.

Screening can lead to anxiety, additional investigations for non-malignant processes, over-diagnosis and treatment of cancers that may never have needed treatment. Over-diagnosis could occur due to lesions that may not progress to invasive cancer during the woman’s lifetime. Some lesions that need investigation based on their imaging features turn out not to be cancer. Providing women with information on risks and benefits can assist them to make informed decisions around screening participation (Cancer Australia 2014).

For more information, see Cancer Australia’s position statement on over-diagnosis.

If a woman is reported as having high mammographic density please refer to the IBIS risk tool.

Symptomatic people

People who have symptoms or signs of breast cancer require prompt investigation of their symptoms, including diagnostic imaging. Screening mammography is not recommended for these people because it may lead to false reassurance and delayed diagnosis.