What You Need to Know About Olivia Munn's Breast Cancer Diagnosis

Three days after her glamorous appearance at the Oscars, Olivia Munn shared that she was diagnosed with breast cancer 10 months ago.

Thirty days after the biopsy that confirmed her condition, she underwent a double mastectomy, according to the details she shared March 13 on Instagram.

"Surprisingly, I only cried twice," wrote Munn, who shares 2-year-old son Malcolm with comedian John Mulaney. "I guess I haven't felt like there was time to cry. My focus narrowed and I tabled any emotions that I felt would interfere with my ability to stay clearheaded."

The 43-year-old thanked Mulaney for supporting her throughout and being there for each of her surgeries—and for making sure the first things she'd see after waking up after a procedure were photos of Malcolm.

"Thank you for fighting so hard to be here for us," Mulaney, 41, commented on her post. "Malc and I adore you."

Notably standing out in Munn's story was how she was diagnosed in the first place: Two months after her routine mammogram came back normal.

In her post she credited her OB/GYN and "guardian angel" Dr. Thaïs Aliabadi for helping her catch the cancer "with enough time" that she had options when it came to treatment. 

Aliabadi, a board-certified physician and host of the SHE MD Podcast, explained Munn's diagnosis to E! News, as well as what patients can do to identify their risk factors for breast cancer, screening options and the never-ending importance of certain healthy lifestyle choices.

When is a mammogram not enough to detect the presence of breast cancer?

Munn shared she had a mammogram that came back normal about a year ago, but two months later—after her OB/GYN calculated her Breast Cancer Risk Assessment score—a subsequent MRI, followed by an ultrasound and then a biopsy confirmed she had cancer.

"In her case, there wasn't a tangible lump, and the lesion was undetectable during the breast exam," Aliabadi, who is also a breast cancer survivor, told E! News in an email interview. "It was only identified through MRI imaging."

Munn also noted that, pre-diagnosis, she had tested negative for 90 different cancer genes, including BRCA, which has been linked to a higher risk of developing breast cancer. (Angelina Jolie cited her positive BRCA1 test as a factor in her choice to undergo a preventive double mastectomy in 2013.)

With Munn seemingly taking all the steps she could to protect herself already, it became even more important for her to share what ultimately led to her diagnosis.

"Unfortunately, today, many women are unaware of their risk," Aliabadi said. "As a physician, I feel I don't have a significant voice, but Olivia, my patient, does. By sharing her story, we hope to raise awareness about this crucial topic and hopefully save countless lives."

What is the Breast Cancer Risk Assessment score?

The score "estimates a woman's risk of developing breast cancer over a certain period based on various factors such as age, family history, reproductive history, and breast density," Aliabadi explained.

Munn's score/lifetime risk was 37 percent, which prompted her doctor to order the MRI.

According to Aliabadi, high-risk patients with a lifetime risk of 20 percent or higher will generally require more "intensive screening measures," such as genetic testing (particularly if there's a family history of breast cancer or other relevant factors), additional imaging (such as 3D mammography "for enhanced surveillance and early protection," breast MRI or ultrasound) and possibly more frequent screening intervals or screenings starting at an earlier age than the typical recommendation of 40.

Patients and their physicians may also discuss "risk-reducing strategies such as chemoprevention (e.g., tamoxifen) or preventive surgery (e.g., mastectomy) for individuals at significantly elevated risk," Aliabadi noted. Tamoxifen is an estrogen receptor modulator given to women and men to prevent breast cancer.

"It's important for patients with a high breast cancer risk assessment score," Aliabadi continued, "to work closely with their healthcare provider to develop a personalized screening and management plan tailored to their individual circumstances and preferences."

There are resources online to learn more, and the OB/GYN also noted the upcoming launch of her SHE MD life-assessment risk calculator to empower women with the information they need to start a conversation with their health care providers about the options that are right for them.

Why are mammograms still so important?

Aliabadi recommends that, starting at age 40, women at average risk should have annual mammograms to detect any abnormalities in the breast tissue.

"High-risk patients can start imaging as early as age 30 to ensure early detection and proactive management of any potential abnormalities," Aliabadi said. "Individuals with a strong family history of breast or ovarian cancer may benefit from genetic counseling and testing to assess their risk."

What is Luminal B cancer?

Munn shared that she was diagnosed with Luminal B, "an aggressive, fast moving cancer," in both breasts.

Aliabadi explained that Luminal B is a subtype of hormone receptor-positive (HR+) breast cancer, which means the cancer cells have receptors for the hormone's estrogen and/or progesterone.

"Luminal B tumors are characterized by higher proliferation rates," she detailed, meaning the cancer cells grow and multiply faster, "and tend to be more aggressive compared to Luminal A tumors—another subtype of HR+ breast cancer."

What are some of the side-effects and other health consequences a patient might experience during and after treatment for breast cancer?

When Munn noted that she'd "only cried twice" after undergoing four surgeries in 10 months, that did seem low—especially considering all the people who probably teared up just reading about her experience.

But while talking about cancer has shed its taboo status—not least due to more people in the public eye opening up about their own experiences—the nitty-gritty of cancer treatment isn't a widely discussed topic.

"Breast cancer treatment and surgery can lead to physical changes like scarring, changes in breast appearance, and swelling in the arm or chest," Aliabadi explained. "Many survivors also experience ongoing fatigue and menopausal symptoms such as hot flashes and vaginal dryness."

Moreover, she continued, "Emotionally, it's tough—feelings of anxiety, depression, and body image concerns are common. Some may notice changes in memory and concentration, too. The financial burden of treatment can be overwhelming, as can the constant worry about the cancer coming back. Having a strong support system is crucial during this time. It's also important to be aware of long-term health risks like osteoporosis and heart disease."

But on a high note, "despite the challenges," Aliabadi concluded, "many survivors find strength and personal growth through their experiences."

What can people do to lessen their risk of developing breast cancer?

You've heard it before, but... 

Quit smoking. 

"Smoking is linked to various types of cancer, including breast cancer," Aliabadi noted. Other lifestyle habits to consider that may lower the risk of developing breast cancer, according to the doctor, include:

Staying physically active, maintaining a healthy weight (being overweight or obese increases the risk of breast cancer, especially after menopause); limiting alcohol consumption (no more than one drink a day, or eliminating altogether); eating a healthy diet rich in fruits, vegetables, whole grains, and lean proteins and limiting intake of processed and red meats.

Knowing your family history is also important, Aliabadi advises, as is following the recommended guidelines for breast cancer screening because early detection can improve outcomes and survival rates.

And, if it's an option, breastfeeding has been associated with a reduced risk of breast cancer, the doctor noted.

In any case, when public figures like Munn share their stories, it gets people thinking. Read on for a sampling of the outpouring of support she received from the likes of Jessica Chastain, Minka Kelly, Julianne Hough and many more:

After Olivia Munn shared her breast cancer diagnosis on Instagram March 13, she received a flood of well-wishes from fans, friends and fellow stars.

"Thank you for fighting so hard to be here for us," the comedian wrote to his partner. "Malc and I adore you."

"Thank you for sharing you brave and courageous soul," the Dancing With the Stars host noted appreciatively. "Saving lives."

"Thank you for sharing this!" the Big Bang Theory actress commented on Instagram. "Wow."

"You are very generous to share your story," the Oscar winner commented on Munn's post. "I believe in doing so, you’ve saved lives. So much love to you and your family."

"I have been thinking about you. Maybe this is why," the veteran jounalist commented on Munn's post. "Sending you love and gratitude for sharing this. And a huge virtual hug."

Couric is also a breast cancer survivor, having gone public with her diagnosis in 2022.

"You are so strong Olivia!" the Fellow Travelers star wrote. "Grateful you found this early. Sending you love always."

"Sending you and your family love & healing vibes," the Modern Family alum commented. "You are so strong."

"Thank you for sharing this and in this way,"  the Friday Night Lights alum commented on Instagram, applauding Munn's detailed story. "You and your strength and vulnerability in equal measure are so beautiful. Sending you biggest love."

"I love you friend," the Emmy winner told her pal. "May God continue to bless you with good health and a long happy life."

"Your experience is so powerful to share!" the Sex and the City actress commented. "Sending you so much love and strength , so grateful you found out early and can only imagine the emotional roller coaster you have been on."

The Office alum commented, "I love you."

"You are brave and strong and I’m thankful you are ok," the Olympic athlete wrote. "Sending all the love."