King Charles III Breaks Silence After Cancer Diagnosis

King Charles III is speaking out for the first time since it was revealed he is battling cancer.

On Feb. 10, five days after Buckingham Palace announced the monarch's diagnosis, the 75-year-old released a personal letter to the public.

"I would like to express my most heartfelt thanks for the many messages of support and good wishes I have received in recent days," the King wrote, as seen in a post shared on the Royal family's Instagram page, which also featured a 2023 photo of the monarch greeting well-wishers. "As all those who have been affected by cancer will know, such kind thoughts are the greatest comfort and encouragement."

The monarch continued, "It is equally heartening to hear how sharing my own diagnosis has helped promote public understanding and shine a light on the work of all those organizations which support cancer patients and their families across the UK and wider world. My lifelong admiration for their tireless care and dedication is all the greater as a result of my own personal experience."

He signed his letter, "Charles R"—his Royal cypher, which stands for "Rex," the Latin word for "king."

His letter was printed on letterhead that read "Sandringham House," the name of the monarch's country home in Norfolk, England.

The King—who has resided at Clarence House in London for years even before he ascended to the throne in 2022 following his mother Queen Elizabeth II's death—flew to Sandringham by helicopter with wife Queen Camilla Feb. 6.

The two had also visited their country estate Feb. 4 to attend a Sunday church service. On Feb. 5, about a week after the King was released from hospital after undergoing a procedure to treat an enlarged prostate, Buckingham Palace announced the monarch has been diagnosed with an unnamed form of cancer . (The Palace told NBC News it is not prostate cancer.)

"During The King's recent hospital procedure for benign prostate enlargement, a separate issue of concern was noted," their statement read. "Subsequent diagnostic tests have identified a form of cancer. His Majesty has today commenced a schedule of regular treatments, during which time he has been advised by doctors to postpone public-facing duties."

Hours before Charles and Camilla departed for Sandringham for their current stay, the monarch met with his son Prince Harry, who had traveled to London from California—where he lives with wife Meghan Markle and their kids Prince Archie, 4, and Princess Lilibet, 2. After a brief visit, the Duke of Sussex jetted back to the United States, where he presented an award at the 2024 NFL Honors event in Las Vegas.

Meanwhile, the King's eldest son and heir, Prince William, recently thanked the public for their support of both his father and his wife Kate Middleton, who is recovering from abdominal surgery.

"I'd like to take this opportunity to say thank you also for the kind messages of support for Catherine and for my father, especially in recent days," the Prince of Wales shared during the London's Air Ambulance Charity Gala Dinner on Dec. 7. "It means a great deal to us all."

A day later, Camilla offered an update on the King's wellbeing during a public appearance at a charity concert at England's Salisbury Cathedral. Per The Telegraph, she told an air ambulance worker, "He is doing extremely well under the circumstances. He is very touched by all of the letters and messages the public have been sending from everywhere. That's very cheering."

Read on for more news from royal families around the world this year:

While King Charles III was in the hospital for his benign prostate enlargement procedure, the royal family member was diagnosed with cancer.

"His Majesty has today commenced a schedule of regular treatments, during which time he has been advised by doctors to postpone public-facing duties," Buckingham Palace said Feb. 5. "Throughout this period, His Majesty will continue to undertake State business and official paperwork as usual.The King is grateful to his medical team for their swift intervention, which was made possible thanks to his recent hospital procedure. He remains wholly positive about his treatment and looks forward to returning to full public duty as soon as possible."

The Duchess of York's rep said in a statement on Jan. 21 that Sarah was recently diagnosed with malignant melanoma, an aggressive form of skin cancer. Several months prior, she underwent a single mastectomy to treat breast cancer.

On Jan. 14, Queen Margrethe II of Denmark made history as she officially abdicated the throne, handing the crown over to her son, now known as King Frederik the 10th. 

Kensington Palace announced on Jan. 17 that Kate Middleton underwent planned abdominal surgery and was set to remain in the hospital for 10 to 14 days.

"Based on the current medical advice," the Palace said, "she is unlikely to return to public duties until after Easter."

Amid Kate's recovery, Prince William postponed a number of engagements as he supported his family, including the couple's three children, Prince George, Princess Charlotte and Prince Louis.

Shortly after Kate's hospitalization was made public, Buckingham Palace shared that Charles "has sought treatment for an enlarged prostate."

"His Majesty's condition is benign and he will attend hospital next week for a corrective procedure," the statement added. "The King’s public engagements will be postponed for a short period of recuperation."

Princess Claire and Prince Felix of Luxembourg welcomed son Balthazar Felix Karl on Jan. 7, the first royal baby of the New Year!

(E! and NBC News are part of the NBCUniversal family.)