Two years after her own diagnosis, Olivia Munn revealed that her mother is now battling breast cancer.
"My mother was diagnosed with breast cancer," the 45-year-old shared in an Instagram post on July 9. "You may know that when I talk about my own battle with cancer I bring up the Lifetime Risk Assessment test that saved my life. I never would've predicted it would save my mom's life as well. ❤️"
Munn explained that after learning she had breast cancer in 2023, she urged her mother to take the Tyrer-Cuzick breast cancer risk assessment.
Based on a variety of factors -- including family history, the date of a woman's first period, breast density and her age when her first child was born -- the free tool estimates a woman's risk of developing invasive breast cancer within the next 10 years and within her lifetime, Dr. Thaïs Aliabadi, a board certified OB/GYN and Munn's doctor, previously told PEOPLE. A lifetime risk score of 20 percent or more suggests high risk, and additional diagnostic screening may be required.
Munn said that her mother scored 26.2% despite having a clear mammogram, so the actress insisted that she get an MRI.
"Shortly after, my mother was diagnosed with stage 1 Her2 breast cancer. She has since completed 12 rounds of chemo and will continue monthly Herceptin transfusions until this fall," Munn wrote. "From my mom being there after my double mastectomy to me being there after hers. From me having to find an oncologist, to my mom and I sharing one. I can tell you this: going through cancer is really hard. But there's something about watching a loved one go through it that is even more heartbreaking."
"My mom's husband , Sam and I learned everything we could about Her2, chemotherapy, immunotherapy, cold caps... I spent many nights taking care of my mom when the chemo became too much, wishing I could fight the fight for her, even if only for a day to give her a little break," she continued. "It's no small feat to realize you can't do it for them. To anyone out there who is taking care of someone or has made it their profession to do so, thank you. These gifts can feel near impossible without you."
Munn's post included several photos and videos throughout her mother's treatment journey, including a clip of her ringing the bell after completing chemotherapy. The X-Men Apocalypse star then stressed the importance of the breast cancer risk assessment test, noting that it "saved my life and now my moms."
"We're taught about our periods, yearly Pap smears and mammograms at 40. And we now need every gynecologist to incorporate the lifetime risk rest into their care plan," she wrote. "All of these things matter, you can't leave one off. My mom wanted me to tell you that she hopes by sharing her story it will help save someone's life."
"I want to say how proud I am of my mom," she added. "She's handled all of this with bravery and humor while still driving us crazy (just says after her double mastectomy she tried to do laundry and make dinner - she’s insane.)"
Munn ended the post by thanking the several people who were a part of her mother's medical team.
Munn was diagnosed with bilateral breast cancer in April 2023. She has since had five surgeries, including a lymph node dissection, a double mastectomy and a hysterectomy.
During the 2025 TIME Women of the Year Gala in February, she said she's "doing really good" as she discussed her treatment and health.
"I'm doing really good today," Munn, who was an honoree at the event, shared. "I am working through different medications and I think anyone who's gone through any kind of cancer but specifically breast cancer understands there's a real science to figuring out the best kind of medication for you."
While Munn admitted "there are good days and bad days," she said that she has "hit a good stride" when it comes to her health.