Kate Middleton, King Charles met privately before she revealed cancer diagnosis

Kate Middleton and King Charles shared a "private lunch" the day before she announced her cancer diagnosis.

His Majesty and the Princess of Wales, who have both begun treatment for cancer, reportedly "met up for lunch" on Thursday, sources told People magazine. 

King Charles is "progressing well" through his ongoing recovery, but the insider added that the royal family is planning ahead for summer without "committing to anything," noting that any events will be "subject to doctors' advice at the time."

KING CHARLES ‘HUGELY FRUSTRATED’ WITH CANCER RECOVERY PROCESS, NEPHEW SAYS

The King "has always had a very good bond with her," author Sally Bedell Smith told the outlet. "She's interested in artistic things, and she appreciates art and culture, so [she] has an affinity with the King over that."

Smith, who penned "George VI and Elizabeth: The Marriage That Saved the Monarchy," said that Charles and Kate now have another shared bond over their cancer diagnosis.

KATE MIDDLETON ANNOUNCES SHE HAS CANCER, UNDERGOING CHEMOTHERAPY TREATMENT

"Obviously they have this in common and can only bring them closer," she noted. "It is a source of reassurance and consolation for both of them."

King Charles III was diagnosed with a form of cancer and is undergoing treatment, Buckingham Palace announced in February. A "separate issue of concern" was identified during Charles' "benign prostate enlargement" procedure at the London Clinic. 

"Subsequent diagnostic tests have identified a form of cancer," the palace said in a statement at the time.

The monarch was "advised by doctors to postpone public-facing duties" while undergoing a series of "regular treatments," a statement from the palace said. It's unclear what cancer diagnosis Charles received.

Buckingham Palace did not immediately respond to Fox News Digital's request for comment.

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In a video shared Friday, the Princess of Wales revealed that she, too, is battling a form of cancer, and has been undergoing preventative chemotherapy treatment.

"It has been an incredibly tough couple of months for our entire family, but I’ve had a fantastic medical team who have taken great care of me, for which I am so grateful," Kate said. "This of course came as a huge shock, and William and I have been doing everything we can to process and manage this privately for the sake of our young family," she continued. "As you can imagine, this has taken time. It has taken me time to recover from major surgery in order to start my treatment. But, most importantly, it has taken us time to explain everything to George, Charlotte and Louis in a way that is appropriate for them, and to reassure them that I am going to be OK.

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"As I have said to them; I am well and getting stronger every day by focusing on the things that will help me heal; in my mind, body and spirits. Having William by my side is a great source of comfort and reassurance too. As is the love, support and kindness that has been shown by so many of you. It means so much to us both."

The Princess of Wales explained that after her abdominal surgery, it was believed her condition was "non-cancerous." However, further testing showed "cancer had been present." She was advised to begin chemotherapy by her medical team.

Middleton has remained out of the public eye since Dec. 25. Buckingham Palace later revealed she had been admitted to a hospital for a planned abdominal surgery on Jan. 17. Since then, she has only been spotted a handful of times, sparking speculation about her whereabouts.

"The Princess will return to official duties when she is cleared to do so by her medical team," a Kensington Palace spokesperson told Fox News Digital. "She is in good spirits and is focused on making a full recovery."