Olivia Munn 'Broke Down' After Double Mastectomy, Cancer Treatment Put Her In Medically-Induced Menopause

While speaking with PEOPLE for its latest cover story, the actress reflected on receiving her "terrifying" stage 1 bilateral breast cancer diagnosis last April, and detailed undergoing four surgeries, including a double mastectomy, almost immediately following it.

"I was not someone who obsessed over death or was afraid of it in any way," said Munn, who shares 2-year-old son Malcolm with partner John Mulaney. "[But] having a little baby at home made everything much more terrifying."

"You realize cancer doesn’t care who you are; it doesn't care if you have a baby or if you don't have time," she added. "It comes at you, and you have no choice but to face it head-on."

The 43-year-old said she had a lymph node dissection, a nipple delay procedure, and a double mastectomy within 30 days after she received her diagnosis.

"I had amazing doctors, but it was still a negotiation sometimes on what we are doing," she told PEOPLE, adding that the nipple delay wasn't a required procedure, and that she was told she had a choice. "But I'm glad I did. I want to give myself the best shot of keeping the parts of me that I can keep."

As Munn previously revealed, she discovered she had breast cancer only three months after taking a genetic test checking for cancer genes and a normal mammogram, which both found no signs of the disease.

"I was walking around thinking that I had no breast cancer," she recalled. "I did all the tests that I knew about."

In March 2023, Munn's OB-GYN calculated her lifetime breast cancer risk score by using the Tyer-Cuzick risk assessment calculator. As PEOPLE noted, a score above 20 percent is high-risk, and Munn's was 37.3 percent. She had an MRI, and the test showed Munn had a spot in her right breast "just a hairline away from my lymph nodes." The Predator star then had an ultrasound, which revealed two more tumors in her right breast. The subsequent biopsy results showed that she had stage 1 invasive cancer.

Following her doctors' recommendation, she decided to have a double mastectomy.

"There's so much information, and you're making these huge decisions for the rest of your life," she said. "I really tried to be prepared, but the truth is that nothing could prepare me for what I would feel like, what it would look like and how I would handle it emotionally. It was a lot tougher than I expected."

When she woke up from her procedure, the New Girl actress said she learned doctors also found a "tangerine-sized" ductal carcinoma in situ (DCIS), a preinvasive cancer inside a milk duct, in her right breast.

"Hearing that news gave me peace that I'd made the right decision," Munn said.

While The Newsroom alum -- who shared that she decided to wait until the following fall to have reconstructive surgery -- said her doctor said she looked "fantastic" after her double mastectomy, she wasn't prepared for what her body would look like.

"I saw myself for the first time and I was in shock. It was incredibly hard," Munn recalled to PEOPLE. "It was a shock. It was a shock to my system. I had such a hard time, I remember just looking in the mirror with him and just having no emotion, just taking in what he was saying."

"When I got home, I undressed and looked in the mirror again, and that’s when I just absolutely broke down," she added.

Munn eventually underwent reconstructive surgery last fall, noting that her body is "much better, but it's not the same, and that's okay."

While she hasn't needed to undergo chemotherapy or radiation, she started hormone suppression therapy, revealing the treatment put her into a medically-induced menopause.

"I'm constantly thinking it’s hot, my hair is thinning, and I'm tired a lot," she explained.

Meanwhile, the Ride Alone 2 star praised Mulaney for his love and support throughout her difficult journey.

"It would've felt like climbing an iceberg without him," she told PEOPLE. "I don't think he had a moment to himself, between being an incredibly hands-on father and going to and from the hospital -- taking Malcolm to the park, putting him to nap, driving to Cedars-Sinai, hanging out with me, going home, putting Malcolm to bed, coming back to me. And he did it all happily."

She also shared that her 2-year-old son has been a source of light for her during the last year.

"When I’m with him, it's the only time my brain doesn’t think about being sick. I'm just so happy with him. And it puts a lot of stuff into perspective," Munn shared. "Because if my body changes, I'm still his mom. If I have hot flashes, I’m still his mom. If I lose my hair, I’m still his mom. That’s really what matters the most to me. I get to be here for him."

Ultimately, Munn said she's "grateful that I was given the opportunity to fight."