"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," the 43-year-old posted on Instagram on March 14.

The Newsroom actor said she took a genetic test in February 2023 that checks for 90 different cancer genes and was negative for all.

Even so, her doctor decided to calculate her Breast Cancer Risk Assessment Score and that "saved my life," Ms Munn said.

Recording a high score of 37 per cent, Munn had imaging tests and got a biopsy, which found she had an aggressive form of cancer in both breasts.

She had a double mastectomy 30 days after the biopsy and has had four surgeries in the past 10 months.

Ms Munn said she revealed her health news in March 2024 because she needed to catch her breath and "get through some of the hardest parts before sharing."

The actor was a correspondent on The Daily Show with Jon Stewart and her movie credits include Magic Mike, The Predator, Office Christmas Party and X-Men: Apocalypse.

She thanked family, friends and her partner, comedian John Mulaney, "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".

The couple made headlines in late 2021 when they announced their pregnancy just months after they were first spotted in public together.

Mr Mulaney's divorce from artist Anna Marie Tendler was announced in May 2021 after the stand-up comedian attended a rehabilitation facility.

On March 6, 2024, Ms Tendler announced the release of her tell-all memoir Men Have Called Her Crazy.

"I have been writing this book for two years. More accurately though I have been writing it for close to four decades. I have never been more proud of any work. It is a story about mental health; about being a woman; about family. And finally, about the endless source of my heartbreak and rage-men," she said.

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