[5 min read] How to assess risk of breast and ovarian cancers

The risk of cancer, particularly breast and ovarian cancers, can cause significant anxiety among women presenting to the general practitioner. Therefore, it is essential to understand the risk factors associated with these cancers and to be able to explain these risks to women.

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The baseline risk of any woman developing breast cancer is approximately 11%, with approximately 1 in 8 Australian women developing breast cancer in their lifetime*. The most significant risk factor for breast cancer is age, with 80% of breast cancers occurring in women over 50. Other non-modifiable risk factors include gene mutations (particularly BRCA1, BRCA2 and TP52), reproductive history and personal and family history of breast cancer.

Significant family history includes women with a family member with a known pathogenic cancer gene variant including BRCA1 and BRCA2, those with a first-degree female relative diagnosed with breast cancer under the age of 40, those with a male first-degree relative diagnosed with breast cancer at any age and those with multiple first or second-degree relatives diagnosed with breast cancer.

Modifiable risk factors for developing breast cancer include taking hormone replacement therapy (HRT), taking the oral contraceptive pill (OCP), smoking, drinking alcohol and being overweight.

The baseline risk of a woman developing ovarian cancer is less than 2%, with approximately 1 in 48 women developing ovarian cancer in their lifetime. The risk factors for ovarian cancer are similar to that for breast cancer, and in fact, risk stratification for breast and ovarian cancer is often combined. Of note, the risk of ovarian cancer appears to be reduced in women using the OCP.

Several risk stratification tools are available, such as iPrevent, a validated breast and ovarian cancer risk assessment and management decision tool. This tool should be used with the patient, using information about their personal history, family history, medications and lifestyle.

The primary clinical purpose of formally assessing breast and ovarian cancer risk is to determine which individuals require a referral to a clinical genetics unit. Most women will fall into the category of “average risk”. These women have a risk of breast cancer <1.5 times the general population risk and generally do not require referral to a clinical genetics unit. Women at “moderate risk” have a 1.5–3 times the population risk of developing breast cancer and may warrant referral for further assessment. Women are termed “high risk” of developing breast cancer if they have more than a 30% lifetime risk of developing breast cancer. This category includes all women with a known BRCA1, BRCA2 or TP53 gene mutation and women with a strong family history. These women should be referred to a clinical genetics unit for further assessment and evaluation.

Aside from assessing risk, it is important to encourage patients to be “breast aware”. Women should be encouraged to perform routine self-examinations to become familiar with their breasts’ natural feel and present promptly where any changes are noted. In addition, it is crucial to ensure that women are aware of screening programs and the importance of attending these.

Lifestyle changes such as stopping smoking, avoiding medications which can increase the risk of breast and ovarian cancer, and maintaining a healthy weight can all contribute to reducing overall risk. Counselling regarding signs and symptoms of both breast and ovarian cancer can enable women to know when to attend primary care for assessment.

– Dr Samantha Miller, MBChB


* Source: https://www.cancer.org.au/cancer-information/types-of-cancer/breast-cancer

  1. National Institute for Clinical Excellence (NICE)(2013). Familial breast cancer: classification, care and managing breast cancer and related risks in people with a family history of breast cancer https://www.nice.org.uk/guidance/cg164/ifp/chapter/how-breast-cancer-risk-is-described
  2. Peter MacCallum Cancer Centre (2023). iPrevent. https://www.petermac.org/iprevent
  3. Queensland Government (2023). How to assess breast cancer risk. https://www.breastscreen.qld.gov.au/health-professionals/how-to-assess-breast-cancer-risk
  4. Royal College of Obstetricians and Gynaecologists. HRT and alternatives. https://www.rcog.org.uk/for-the-public/menopause-and-later-life/hrt-and-alternatives/
  5. Australian Government: Department of Health and Aged Care. BreastScreen Australia Programme. https://www.health.gov.au/initiatives-and-programs/breastscreen-australia-program
  6. Cunliffe, A & Simcock, R (2016). Breast cancer in primary care. British Journal of Family Medicine. https://www.bjfm.co.uk/breast-cancer-in-primary-care
  7. Cancer.org (2021). Ovarian Cancer Risk Factors. https://www.cancer.org/cancer/ovarian-cancer/causes-risks-prevention/risk-factors.html



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