Olivia Munn recently revealed she’s been receiving treatment for breast cancer. Munn, who is 43, shared more about her diagnosis and how it came to be in an Instagram post.

“In February of 2023, in an effort to be proactive about my health, I took a genetic test that checks you for 90 different cancer genes,” Munn wrote. “I tested negative for all, including BRCA (the most well-known breast cancer gene). My sister Sara had just tested negative as well. We called each other and high-fived over the phone. That same winter I also had a normal mammogram. Two months later I was diagnosed with breast cancer.”

Munn went on to share that she would not have been diagnosed for months until her next annual mammogram — but her OB/GYN calculated her breast cancer risk assessment score, which changed the course of her screening approach.

“Dr. Aliabadi looked at factors like my age, familial breast cancer history, and the fact that I had my first child after the age of 30. She discovered my lifetime risk was at 37%. Because of the score I was sent to get an MRI, which led to an ultrasound, which then led to a biopsy. The biopsy showed I had Luminal B cancer in both breasts,” Munn wrote.

A simple test — along with guidance from an attentive doctor — may have saved Munn’s life…and maybe her speaking out about it could save someone else’s too. 

There’s so much to Munn’s story that’s important to talk about, from her own risk factors to the screening methods that were used to detect her cancer. In sharing her story, Munn is bringing awareness to so many aspects of breast cancer screening and detection.

We asked Jaime Knopman, MD, a board-certified reproductive endocrinologist and breast cancer survivor, to break it all down.

How can we calculate someone’s breast cancer risk?

“The Breast Cancer Risk Assessment Tool (called the BRCAT or the Gail Model) calculates a woman's risk of developing invasive breast cancer in the next five years and up to age 90,” says Dr. Knopman. “Select risk factors (age, family history, age at first birth) are put into the calculator; the data generates the patients 5 year risk of developing breast cancer and the lifetime risk of developing breast cancer.”

Dr. Knopman believes this tool can be helpful for doctors to determine a patient’s approach to breast cancer screening, but it’s not the only one factor. She adds that family history of breast cancer, genetic mutations (like the BRCA 1 or BRCA 2 genes), personally or in family members, ethnicity, age, age at first birth, never being pregnant, early menarche, and late menopause are other risk factors that may make someone a candidate for increased screening. 

Munn mentioned that her doctor calculated her risk profile, but according to Dr. Knopman, people can run these calculations on their own at home. With that being said, there’s more to it than the results of an online risk assessment tool.

“Knowing who and when to screen is not as easy as putting some data into a calculator,” says Dr. Knopman. “It is important to speak with a medical professional and truly understand your risks and how best to screen. While it isn't a bad place to start and might motivate someone to see their doctor, [it] should not be the only screening tool someone does.”

We are always in favor of women taking more control of their health, and an awareness of your personal risk profile where breast cancer is concerned is so important. After all, standard screening guidelines are not necessarily right for everyone across the board, and Munn’s story is such a powerful testament to that.

What role does age at first delivery play?

One point Munn makes in her Instagram post revealing her diagnosis is that because she had her first baby after age 30, she was at higher risk for breast cancer. This may have other women who gave birth after 30 worried about what this means for their own risk.

“Early age at first pregnancy is protective,” Dr. Knopman says. “The immature breast tissue (pre pregnancy and breastfeeding) is different than the mature breast tissue. The immature tissue responds differently to hormones. Pregnancy and breastfeeding make the cells more mature and therefore their response to hormones is altered.”

“The monthly hormonal rise and fall of estrogen and progesterone does not occur [during pregnancy], and this is protective for ovarian and uterine cancer,” adds Dr. Knopman. “Furthermore, pregnancy induces changes in the breast tissue which could change the cell transformation and reduce the risk of developing breast cancer.”

But is a woman’s risk the same if she delivers at age 30 vs. say, age 40? This is unclear, but it’s important to remember that age at first birth is one piece of the puzzle. All pieces are significant, says Dr. Knopman.

Can genetic testing really pin down a person’s risk?

Another piece Munn mentions is genetic testing. In her Instagram post, she revealed that she was screened for 90 different cancer genes, and tested negative for all of them. Are genetic tests actually effective markers of someone’s cancer risk?

They can be, according to Dr. Knopman. “It is not the only way but it is a great way to identify if you have genetic markers for developing cancer,” she says. “We routinely send such tests in patients with strong family histories for cancer. This is why [thinking about] family history is so important! I always ask patients about their families health and cancer history.”

Screening beyond mammograms

When you think about breast cancer screening, mammograms are probably what initially come to mind. But, as Munn’s story indicates, it's not the only test. Munn revealed she had an MRI and ultrasound before her biopsy, which confirmed the presence of cancer. 

According to Dr. Knopman, ultrasound and MRI screening are “most definitely” a good idea for high-risk women. 

“Personally this was how my cancer was detected,” she says. “I had an annual mammogram that was normal but my ultrasound detected a mass. It was biopsied and found to be a stage I invasive breast cancer. MRI and ultrasounds are particularly helpful for women with dense breasts.”

Why early detection is so important

Early detection is so important — as Munn says, if she and her doctor had not focused on a more individualized approach, her cancer wouldn’t have been detected for another year.

“If detected early you can change the course of the disease,” says Dr. Knopman. “Early stage cancer is curable. The earlier a tumor is detected the better the prognosis, and the lower the chance for future metastatic disease.”

“I feel grateful everyday that I was diagnosed as a stage I,” she adds. “The five-year survival rate for an early stage breast cancer is 99%. The five-year survival rate with stage IV distant metastatic rate (aka spread to a different area in the body) is only 29%.”

Like Munn, Dr. Knopman credits thorough screening for saving her life and changing the course of her disease and management.

“Screening effectively saved my life,” she says. “If I had not gone for my annual mammogram and ultrasound because I had dense breasts, I am not sure when my cancer would have been identified.”

Zara Hanawalt is a freelance journalist and mom of twins. She's written for outlets like Parents, MarieClaire, Elle, Cosmopolitan, Motherly, and many others. In her (admittedly limited!) free time, she enjoys cooking, reading, trying new restaurants, and traveling with her family.