What a breast cancer risk calculator can and cannot tell you

This week, actress Olivia Munn shared that she was diagnosed and treated for breast cancer last year, and that a risk calculator helped her doctor detect the cancer early.

“Ask your doctor to calculate your breast cancer risk assessment score,” Ms. Munn urged the audience in her post.

Medical experts are enthusiastic about the attention to risk calculators, but warn that the results are only rough estimates and should be interpreted with the help of a doctor. Here’s what you need to know.

What do breast cancer risk calculators take into account?

About one in eight women will develop breast cancer during her lifetime. But tools like those provided by Ms. Munn’s doctor can provide a more personalized view of an individual patient’s risk.

There are two main calculators: the Breast cancer risk assessment toolalso known as the Gail model, and the Tyrer-Cuzick Risk Assessment Calculator, also called the IBIS model. Both ask users about their age, race, ethnicity, family history of breast cancer, when they first got their period and, if they have children, how old they were when they had their first child. All of these factors can influence a person’s risk of breast cancer.

The IBIS calculator also asks for information about an individual’s biopsy history, breast density, and the age at which family members were diagnosed with breast cancer.

The calculators compare a person’s answers to the average of other women from the same age and racial group, and use that to estimate the five-year and lifetime risk of developing breast cancer.

Although men can also get breast cancer, the tools only calculate the risk for women. The Gail model cannot accurately calculate the risk for women with a history of invasive breast cancer or ductal carcinoma in situ or women with mutations in the BRCA1 or BRCA2 genes, which increase the risk of breast cancer, said Dr. Sandhya Pruthi, specialist in chest medicine. the Mayo Clinic Comprehensive Cancer Center. Accuracy may also vary for different racial groups. “These things were originally built around women from Western Europe,” says Dr. Otis Brawley, associate director of community outreach and engagement at the Sidney Kimmel Comprehensive Cancer Center.

According to the National Cancer Institute, the Gail calculator may underestimate the risk in black women with previous biopsies and Hispanic women born outside the United States. It may also be inaccurate for American Indian or Alaska Native women because data on their risks is limited. Black women can ask their doctors about the Black Women’s Health Study Calculatorwhich was developed using data from black women in the United States.

It’s also essential to make sure you understand the data needed to answer the questionnaires and enter them correctly, said Dr. Pruthi. Even small changes in the answers can produce vastly different risk scores. And experts noted that these calculators should be used as part of broader care, including regular doctor appointments and recommended screenings such as mammograms. They can also be helpful for women who are not yet old enough to undergo routine mammograms.

How do you interpret the risk score?

Breast cancer risk calculators should be used as a conversation starter with a healthcare provider, said Dr. Nancy Chan, an oncologist and director of breast cancer clinical research at NYU Langone’s Perlmutter Cancer Center. Knowing your risk assessment can help you and your doctor discuss whether you may need more frequent mammograms or genetic testing, or whether certain preventive measures may help lower your risk.

“If you are at high risk, we can actually do something about that,” she added. Doctors may recommend that women with a high score make certain lifestyle changes – such as exercising more, cutting back on smoking and reducing alcohol intake – or that those at high risk have a five-year medications that can help reduce the risk of breast cancer.

However, doctors warn that interpreting your score on your own can be difficult. In particular, the difference between the five-year risk score and lifetime risk can be difficult to understand, said Dr. Brawley.

“One of the things I worry about is that a woman will take the test and have a lower-than-average risk of breast cancer — say, a 7 percent lifetime risk — and decide, ‘Oh, then I am not in a program of routine, high-quality screening,” said Dr. Brawley. Other women may receive a higher risk score which, if interpreted without other context, could lead to over-testing or unnecessary anxiety.

“You don’t want people to just look at these numbers and get unnecessarily scared,” said Dr. Steven Woloshin, a professor of medicine at Dartmouth University who has studied overdiagnosis.

A risk score cannot determine whether or not a person will develop breast cancer. And it says nothing about your chances of dying from the disease, said Dr. Woloshin.

Other risk assessment tools are being developed that could help doctors make even stronger predictions in the future, said Dr. Pruthi. “Where we ever really want to be is at personal risk,” she said. “What new information can we add that is more unique to you?”