Olivia Munn's doctor did a test as a precaution. It 'saved her life'.

Olivia Munn has been diagnosed with breast cancer.

The actress, 43, shared a series of photos on Instagram showing herself undergoing treatment in the hospital.

Watch: John Mulaney announces he is expecting a baby with Olivia Munn. Post continues below.

"I was diagnosed with breast cancer," read the caption. "I hope by sharing this it will help others find comfort, inspiration and support on their own journey."

Munn disclosed that she and her sister underwent genetic testing for 90 different cancer genes including BRCA, the most well-known breast cancer gene.

Although both Munn and her sister tested negative for the gene and received clear mammograms, her doctor opted to calculate her Breast Cancer Risk Assessment Score as a precautionary measure.

"The fact that she did saved my life," wrote Munn, revealing that her calculated risk was 37 per cent.

As a result of that percentage, she was scheduled for an MRI, ultrasound and biopsy, with the results showing that she had Luminal B cancer in both breasts.

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Munn described it as an "aggressive, fast-moving cancer" in her post. Within the span of a month, Munn underwent a double mastectomy, followed by a total of four surgeries over a period of 10 months.

"I went from feeling completely fine one day, to waking up in a hospital bed after a 10-hour surgery the next," she wrote. "I’m lucky. We caught it with enough time that I had options."

The actress thanked her loved ones for their support and for staying by her side throughout her many surgeries, including her boyfriend and father to her two-year-old son, Malcolm, John Mulaney.

"I'm so thankful to my friends and family for loving me through this. I'm so thankful to [Mulaney] for the nights he spent researching what every operation and medication meant and what side effects and recovery I could expect," she wrote. 

"For being there before I went into each surgery and being there when I woke up, always placing framed photos of our little boy Malcolm so it would be the first thing I saw when I opened my eyes."

"Thank you to the friends who've had breast cancer and the friends who connected me to friends who've had breast cancer for guiding me through some of my most uncertain and overwhelming moments," Munn added.

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

Munn and Mulaney began dating three years ago, but didn't make their red carpet debut together until January 2024.

Munn concluded her post by thanking all the health professionals who guided her throughout this difficult journey, including her OBGYN, Dr Thaïs Aliabadi, whom she called her "guardian angel".

Feature Image: Instagram @olivamunn.

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