Olivia Munn was secretly diagnosed with breast cancer in February 2023.

The 43-year-old actress received news that she was suffering from the disease just over 12 months ago, but decided to keep it to herself and on Wednesday, revealed for the first time that she had undergone a double mastectomy after a risk assessment test saved her life.

She wrote on Instagram: "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.

"I tested negative for all, including BRCA (the most well-known breast cancer gene).

"My sister, Sara [Potts] had just tested negative as well. We called each other and high-fived over the phone. That same winter I also had a normal mammogram.

"Surprisingly, I’ve only cried twice.

"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 clear-headed."

The “Newsroom” star, who has two-year-old son Malcolm with husband John Mulaney, explained that her cancer would have gone unnoticed until her next routine mammogram, but her doctor decided to do a simple risk assessment test based on factors such as her age, medical history and the fact that she had her first child over the age of 30.

After Munn found out that she held an almost 40 percent chance of developing cancer within her lifetime, she went for an MRI which led to further tests confirming the disease.

She said: "I wouldn't have found my cancer for another year at my next scheduled mammogram - except that my OBGYN, Dr. Thaïs Aliabadi, decided to calculate my Breast Cancer Risk Assessment Score. The fact that she did saved my life.

"Dr. Aliabadi looked at factors like my age, familial breast cancer history, and the fact that I had my first child after the age of 30. She discovered my lifetime risk was at 37%. Because of that score I was sent to get an MRI, which led to an ultrasound, which then led to a biopsy.

"The biopsy showed I had Luminal B cancer in both breasts. Luminal B is an aggressive, fast moving cancer."

Munn concluded her post by reflecting that she went from feeling "completely fine" one day to being in surgery the next and noted that she has been "lucky" but urged other women to undergo a Breast Cancer Risk Assessment Score and to take action if their score is revealed to be more than 20 per cent.

She added: "30 days after that biopsy I had a double mastectomy. I went from feeling completely fine one day, to waking up in a hospital bed after a 10-hour surgery the next.

"I'm lucky. We caught it with enough time that I had options. I want the same for any woman who might have to face this one day.

"Ask your doctor to calculate your Breast Cancer Risk Assessment Score. Dr. Aliabadi says that If the number is greater than 20 per cent, you need annual mammograms and breast MRIs starting at age 30."

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