This risk assessment tool helped Olivia Munn discover her breast cancer

Olivia Munn in hospital during breast cancer battle
Actress Olivia Munn said on social media March 13 that she'd been diagnosed with breast cancer. Photo credit: @oliviamunn / Instagram

A tool that's available as an online calculator played a key role in actress Olivia Munn's discovery that she had breast cancer – even after she had "a normal mammogram," according to a post on social media.

The X-Men: Apocalypse star, 43, wrote to Instagram on Wednesday (local time) that she was diagnosed with breast cancer last year and would not have discovered it if her physician, Dr Thaïs Aliabadi, had not calculated her breast cancer risk score.

Using that assessment, Aliabadi discovered that Munn's lifetime risk for breast cancer was 37 percent. Because of that score, Munn had additional evaluations, leading to her diagnosis, according to her post.

A breast cancer risk assessment tool uses a statistical model to estimate a woman's risk of developing breast cancer over the next five years as well as over her lifetime, or up to about age 90, according to the National Cancer Institute

The tool typically involves several questions about the person's medical history, reproductive history and family history. Although it's usually used by health professionals, patients can also complete the assessment online.

Two models are commonly used as breast cancer risk assessment tools: the Gail Model and the Tyrer-Cuzick Risk Assessment Calculator. An online version of the breast cancer risk assessment tool, using the Gail Model, is available for anyone to take at It reveals the patient's estimated five-year risk and lifetime risk of developing breast cancer, alongside the average risk for women in the United States of her age and race.

"Although a woman's risk may be accurately estimated, these predictions do not allow one to say precisely which woman will develop breast cancer. In fact, some women who do not develop breast cancer have higher risk estimates than some women who do develop breast cancer," according to the National Cancer Institute's website.

'Every woman should know' their risk 

A family history of breast cancer or other cancers is usually why a physician might conduct a breast cancer risk assessment for their patient, and that is pretty common for a doctor to do, said Dr Jennifer Plichta, director of the Breast Risk Assessment Clinic at the Duke Cancer Institute in Durham, North Carolina.

"I personally think every woman should know what their risk of breast cancer is. I don't care if you think you're low risk or high risk. I think it's worth at least one discussion. Generally, a lot of the organizations are actually saying that conversations should start around the age of 25," Plichta said.

"When your doctor asks you a bunch of questions and it seems like they're being nosy, they're actually probably doing some kind of informal risk assessment in their head," she said. "Then, you might take that next step of doing what we call a formal risk assessment, and you start using a mathematical model that has been developed to determine a woman's risk."

If someone conducts their own risk assessment online, they should discuss their results with their doctor, Plichta said. 

"Anybody who does one of these risk assessments online should probably then follow it up with a conversation with their provider, just to make sure that they're understanding the meaning of what they found out and to make sure that they did it correctly," Plichta said.

"There are definitely times where I've had patients who we thought might be high risk, and I ran a little bit more of a nuanced or detailed risk assessment, and they weren't. And I've also had the opposite happen," she said. "So, I think the online tools are great for initiating a discussion. Some of these online models are a little bit generic. They're helpful, they definitely have a role, and it's a good place to start – but I don't think I would end the conversation there."

A breast cancer risk assessment tool typically asks for a patient's age, the age of their first menstrual period, whether they've had a breast biopsy, the age at which they may have had a full-term pregnancy and their family history of breast cancer, among other factors, Dr Otis Brawley, a professor of oncology and epidemiology at Johns Hopkins University, said in an email Wednesday.

All those factors are entered into an algorithm that calculates the risk score. Some people may score high even if they don't have known gene mutations associated with increased breast cancer risk. 

"It is a way of figuring out who is high risk and who is normal or low risk," Brawley said, adding that the average risk for a woman in her 40s is typically 0.9 percent for five years and about 12 percent for her lifetime.

"It has some caveats, such as it may underestimate risk in Black women with previous biopsies and Hispanic women born outside the US," Brawley said of the assessment tools.

"I prefer women do this with a doc or genetic counsellor who knows the drawbacks," he said. "The tool is useful but can make a woman worry her risk is greater than it really is or give false assurance that someone is low risk."

Someone who scores high on a breast cancer risk assessment might be recommended for additional evaluations of the breast besides a typical mammogram, an X-ray picture of the breast. 

In Munn's case, she was sent to get an MRI or magnetic resonance imaging of the breast, which led to an ultrasound and then to a biopsy, she wrote in her Instagram post.

"The reason that a person could have an MRI would be because they're calculated to have a higher risk of breast cancer on the basis of the mathematical model," said Dr Larry Norton, a breast oncologist and medical director of the Evelyn H. Lauder Breast Center at Memorial Sloan Kettering Cancer Center.

Mammograms evaluate two things, he said: the density of the breast tissue and calcifications in the breast, which are calcium deposits within breast tissue.

However, "MRIs look for blood vessels, because one of the things that cancers do when they become cancerous is, they develop abnormal blood vessels," Norton said. 

"So, MRIs supplement mammograms. They don't replace mammograms in most people," he said. "In many high-risk individuals now, we do both mammograms, and we do MRIs."

For some women, a breast risk assessment tool may not be as accurate or appropriate, Robert Smith, senior vice president of early cancer detection science for the American Cancer Society, said in an email Wednesday.

"A woman should note disclaimers about the use of the tool in women with a history of breast cancer, or who is a mutation carrier of a breast cancer susceptibility gene. If a woman has a history of multiple first and or second-degree relatives diagnosed with breast cancer, this tool is not appropriate for them," he wrote.

"For a woman at higher risk due to her family history, there are tools that are tailored for her circumstance," he said. "Most women fall into a range of risk that is average, and the tool would not suggest that they should be screened any differently than currently recommended." 

Olivia Munn writing about her diagnosis - her candid post to Instagram
Olivia Munn opened up about her diagnosis in a candid post to Instagram earlier this week. Photo credit: @oliviamunn / Instagram

When to screen for breast cancer

In a draft recommendation last year, the US Preventive Services Task Force proposed that all women at average risk of breast cancer start screening with mammograms at age 40 to reduce their risk of dying from the disease.

The USPSTF is a group of independent medical experts whose recommendations help guide doctors' decisions and influence insurance plans, and that draft recommendation aligns with what some groups, such as the American Cancer Society, have been recommending: for average-risk women to start mammograms in their 40s.

The American Cancer Society recommends that women who are at high risk of breast cancer based on certain factors get a breast MRI and a mammogram every year, typically starting at age 30. 

Having access to a breast cancer risk assessment tool empowers patients, Dr Ruth Oratz, a breast medical oncologist at NYU Langone Health's Perlmutter Cancer Center and clinical professor of medicine at the NYU Grossman School of Medicine, said in an email Wednesday.

"Having information empowers patients. It is very important for people to be aware of their health risks, their family history, and their own personal medical conditions. All these things can affect the risk of developing cancer," she said.

"Depending on level of risk, and the factors that contribute to that risk, women can take steps to help lower the possibility of developing breast cancer. It is important to have a healthy body weight and not be overweight. It is important to eat a healthy diet that is not overloaded with sugar and fat. Alcohol is a significant risk factor for breast cancer, and we recommend that women do not drink alcohol every day and have no more than one or two drinks on the days that they do drink," Oratz said.

"We certainly recommend that people do not smoke. Remaining physically fit with exercise and some weight training to maintain muscle mass and strength also contributes to general overall health," she said. "Sometimes medications are given to help reduce the risk of breast cancer. Each individual needs to discuss this with a breast cancer expert."