The Monarch has recorded a personal message concerning his battle with cancer, scheduled for transmission as part of this year's Stand Up To Cancer initiative, run by a leading cancer charity and a major network.
Buckingham Palace said the King would talk about his "healing process" as a individual battling cancer, in a recorded address on Friday at 20:00 GMT.
The message, recorded at Clarence House a fortnight ago, will highlight the importance of routine screenings to increase the likelihood more people catch the condition at an early stage.
This represents a uncommon insight on the medical condition of the Monarch, who has been in a course of therapy since the news was shared in the start of 2024. Analysts suggest doubtful the King will disclose his type of cancer.
The Stand Up To Cancer campaign each year raises funds for scientific studies and therapies and urges people to get screenings to boost the probability of an prompt identification.
The King's candid approach about his health challenge, and living with cancer, has been designed to raise awareness and to encourage more people to get checked - and this will be taken a step further with this unusual direct participation.
To date the King's key philosophy to his cancer has been to continue his schedule, upholding a hectic timetable alongside his frequent sessions of therapy, and he appears not to have desired to be characterised by his diagnosis.
The past twelve months has seen the King, 77, undertaking several international tours, notably to Italy and Canada, and receiving the largest volume of official guests to the UK for a generation, featuring the German president last week.
Friday evening's awareness programme on the network, hosted by well-known figures like several TV personalities, will appeal to people not to be frightened of getting cancer checks.
The hosts have been had experience with cancer - McCall disclosed in November she had received treatment for breast cancer, while another presenter was treated for the illness more than 15 years ago. Comedian Adam Hills has previously discussed his parent, who had one form of cancer and then later leukaemia.
The broadcast will reach out to the roughly millions of people in the UK who charities says are not current with public health checks, with an digital tool to let people check if they are eligible for tests for several common cancers.
In an bid to clarify cancer checks and illustrate the importance of early diagnosis there will be a real-time transmission from treatment centres at medical facilities in Cambridge.
"My aim is to remove the anxiety surrounding preventative tests and show the public that they are not isolated in this," said a presenter.
Currently in the UK, there are several key national health screening services - for major health concerns - accessible for specific demographics.
A new lung cancer screening programme is also being gradually implemented for anyone at increased risk of developing the condition, specifically targeting people in a specific age bracket, who have a smoking history or have smoked in the past.
Men may discuss prostate screenings, but there is lacking a standardised service currently available.
The fundraising initiative, which has collected £113m since 2012, is funding 73 medical projects involving 13,000 patients.
His Majesty, in a statement for attendees at a reception for cancer charities in the spring, had spoken of acknowledging the "overwhelming and at times scary reality" for cancer sufferers and their loved ones.
But he noted his first-hand encounter of coping with cancer had shown him that "periods of great challenge of disease can be illuminated by the support of carers," as he thanked those who supported cancer patients.
The Palace has not disclosed what kind of cancer the King has, or what treatment he has undergone. The King's cancer was detected after he had undergone a medical treatment.
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