So I’ve been getting a lot of questions this past week about breast cancer and breast cancer risk assessment. Recently actress Olivia Munn shared publicly about her breast cancer diagnosis, and how it was found after she had a breast MRI due to an elevated risk on an assessment tool performed by her doctor. I’m very sorry to hear about her cancer diagnosis but I think she is being very courageous in sharing her story and encouraging women to learn more about their risk.
So – what is a breast cancer risk assessment tool and when or why would someone want to use one? Let’s start with some numbers. The lifetime risk for women of being diagnosed with breast cancer is 12% – higher than some might think. We can divide women into three categories – average risk (below 15% lifetime risk) moderate risk (15-20%) and high risk (greater than 20%) Fortunately for all of these categories the risk of dying from breast cancer is much lower, due to early diagnosis and effective treatments.
What drives risk? Age is a significant risk factor. This is why we start mammograms using an age based recommendation for average risk women. Other factors that increase risk include a family history, race/ethnicity, being overweight or obese, drinking alcohol, age at first menstrual cycle, hormone use, history of benign breast disease, and age at first childbirth and number of births – taller height is even a modest risk factor! There are several well validated risk assessment tools out there that can help you and your doctor estimate risk.
- The National Cancer Institute’s Breast Cancer Risk Assessment Tool (Gail Model)
- The Breast Cancer Surveillance Consortium Risk calculator
- Tyrer-Cuzick Model (International Breast Cancer Intervention Study)
Keep in mind that the risk factors aren’t all equal – different risk factors carry stronger weights. Family history, for example having a mother or sister with breast cancer, is a much stronger risk factor than having your first child after age 35. The different models also use different inputs – the Gail Model is relatively quick, the Tyrer-Cuzick takes a lot more time – especially if you have a large family. Not all models are appropriate for women with risk factors like known BRCA mutations or a history of chest radiation for prior cancers. While these are all available online it’s important to review your risk and history in conjunction with your doctor to make sure you’re using the most appropriate tool for your situation. .
For women with a lifetime risk over 20%, the recommendation is to offer supplemental screening with breast MRI in addition to mammograms. MRIs are more sensitive than mammograms – they will pick up more cancers, but may also bring more false positive results. This is why we don’t recommend them for everyone under our current guidelines. Many higher risk women who know about a genetic test risk or strong family history will be offered a referral to a high-risk breast clinic, to discuss options for screening and further genetic testing. However, it’s becoming increasingly common for me to assess risk and order breast MRIs in primary care – I don’t want a referral to a specialist to be a hurdle to getting women screening they need. Hopefully the recent news coverage will empower more women to talk to their doctors about assessing their risk and making sure they’re getting the appropriate screenings they need.