AceShowbiz - Olivia Munn revealed in March 2024 that she had been privately battling breast cancer since 2023. The actress and former The Newsroom star shared an open letter on Instagram detailing the discovery of her luminal B breast cancer and her reasons for keeping the diagnosis confidential for nearly a year. Since making the announcement, Olivia Munn has been updating fans about her health journey and advocating for breast cancer awareness.

In her March 13, 2024 Instagram post, Olivia Munn recounted how her cancer was found following a genetic test. She explained, "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." Two months later, she received her breast cancer diagnosis. Over the past ten months, she has undergone four surgeries and faced many difficult days, yet she has only cried twice. Olivia described how she chose to present herself publicly only when she had the energy to do so, while keeping the diagnosis and treatment struggles private.

The decision to delay sharing her diagnosis was driven by a need to process the hardest moments first. Olivia Munn wrote, "I needed to catch my breath and get through some of the hardest parts before sharing." She credited her OBGYN, Dr. Thais Aliabadi, for saving her life by calculating her breast cancer risk assessment score, which led to an earlier diagnosis than she would have had at her next scheduled mammogram.

Dr. Aliabadi evaluated factors including family cancer history and Olivia's childbirth after age 30, calculating a 37 percent lifetime risk for breast cancer. This prompted further testing—an MRI, ultrasound, and biopsy—that confirmed luminal B cancer in both breasts. Olivia described the abrupt transition from feeling healthy to undergoing a 10-hour double mastectomy 30 days after the biopsy.

Despite the aggressive nature of luminal B cancer, Olivia Munn feels fortunate that the disease was caught early enough to allow treatment options. She emphasized her desire for other women to have that same opportunity if faced with breast cancer someday.

According to City of Hope’s cancercenter.com, luminal B breast cancer expresses estrogen or progesterone hormone receptors but does not express HER2 proteins. It is more aggressive than luminal A cancer, often growing faster and associated with a poorer prognosis due to the presence of HER2 proteins in some cases.

Olivia Munn has undergone multiple surgeries as part of her treatment plan, including the double mastectomy and a hysterectomy. She is also receiving hormone suppression therapy and has preserved her fertility by freezing her eggs. In interviews, including one with CBS, she shared that while her treatment continues, she is recovering well and remains committed to raising awareness about early detection.

Alongside her health battle, Olivia is focused on family life with her husband, comedian John Mulaney, and their two children. They welcomed their son Malcolm Hi?p Mulaney in November 2021, prior to the cancer diagnosis. Their daughter, Méi June Mulaney, was born via surrogate in September 2024.

In February 2025, Olivia Munn publicly reflected on her ongoing treatment, noting that she still has "years to go" but is feeling healthy. At TIME’s Women of the Year gala, she toasted "to good health [and] to healthy days" and shared a heartfelt story about her daughter Méi’s recent stomach discomfort. Trusting her maternal instincts, Olivia switched Méi’s formula, leading to rapid improvement. She described this moment as one of her proudest experiences as a mother and expressed gratitude for her own health on that day.

Despite the challenges, Olivia Munn has maintained a public presence, attending high-profile events such as the 2024 Oscars shortly before announcing her diagnosis. She has also walked red carpets with John Mulaney, including the SNL 50: The Anniversary Special.

Through her openness, Olivia aims to encourage other women to prioritize breast health and seek early screenings. Her story underscores the importance of proactive risk assessment and the impact of early intervention in breast cancer treatment.