Jared Kushner secretly battled thyroid cancer and had surgery to remove a tumor in his throat while serving as a top White House adviser to his father-in-law and former US President Donald Trump.

Kushner, 41, kept the illness out of the headlines and even attempted to keep it a secret from then-President Trump, he writes in chapter 37 of “Breaking History: A White House Memoir,” which hits shelves on August 23.

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Kushner wrote that he learned that he likely had cancer in October 2019 during trade talks with China that ultimately resulted in a “phase one” agreement to back away from tariffs”.

“As this high-wire act of trade talks with the Chinese progressed, I had to confront an unexpected and frightening personal problem,” Kushner wrote.

“Every night, before I went to bed, I lingered for a few extra moments in my children’s rooms. I watched them sleep without a care in the world. I felt guilty that I had been so distracted and absent over the previous few years,” Kushner wrote.

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“I was always at work or taking phone calls when they wanted to spend time with their dad. I missed plays and sporting events. I had promised myself that when my service in the White House ended, I’d make up for lost time. Now I was forced to confront that possibility that my time might be up. I prayed that the surgery would be successful.”

His father-in-law found out about the operation despite the attempted secrecy.

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“The day before the surgery, Trump called me into the Oval Office and motioned for his team to close the door. ‘Are you nervous about the surgery?’ he asked,” Kushner wrote.

“‘How do you know about it?” Kushner asked.

“‘I’m the president,'” Trump replied, according to Kushner. “I know everything. I understand that you want to keep these things quiet. I like to keep things like this to myself as well. You’ll be just fine. Don’t worry about anything with work. We have everything covered here.”

Kushner’s cancer diagnosis was first reported by the New York Times on July 25.

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Kushner and his wife Ivanka worked as unpaid advisers during Trump’s four years in office and he wielded substantial influence over domestic policy debates, staffing decisions and even foreign affairs.

Notably, Kushner was involved in brokering the US-Mexico-Canada (USMCA) trade agreement in 2018 and helped lead the White House coronavirus response in 2020, including the successful development of vaccines within less than a year.