The Monarch has taped a personal message about his journey with cancer, scheduled for transmission as part of this year's fundraising initiative, run by Cancer Research UK and Channel 4.
The royal household said the King would reflect on his "healing process" as a individual battling cancer, in a televised statement on Friday at 8pm UK time.
The recording, recorded at his London residence two weeks ago, will stress the importance of cancer screening checks to increase the likelihood more people diagnose the illness at an initial point.
This represents a uncommon insight on the health of the King, who has been in a course of therapy since revealing his diagnosis in February 2024. But it is thought doubtful the King will identify his specific form of cancer.
The Stand Up To Cancer campaign each year collects money for medical research and patient care and urges people to get screenings to increase the odds of an early diagnosis.
The King's relative openness about his health challenge, and living with cancer, has been designed to increase understanding and to get more people to get tested - and this will be escalated with this unique royal involvement.
To date the King's key philosophy to his cancer has been to maintain his duties, maintaining a hectic timetable alongside his regular rounds of care, and he is understood not to have desired to be defined by his condition.
The past twelve months has seen the Sovereign, taking several overseas trips, including to Italy and Canada, and hosting the largest volume of inward state visits to the UK for decades, which included the German president recently.
This Friday's Stand Up to Cancer show on Channel 4, featuring well-known figures like a team of famous hosts, will urge people not to be afraid of getting preventative tests.
All three have been affected by cancer - Davina McCall revealed last month she had received treatment for the disease, while Clare Balding was treated for thyroid cancer more than 15 years ago. Presenter Hills has previously discussed his father, who had a diagnosis and then later leukaemia.
The programme will appeal to the estimated nine million people in the UK who charities says are not up to date with national health programmes, with an website to let people determine if they are able for screenings for breast, bowel and cervical cancer.
In an effort to clarify screenings and show the importance of early diagnosis there will be a live broadcast from treatment centres at two Cambridge hospitals in Cambridge.
"I want to reduce the stigma out of health checks and demonstrate everyone that they are not alone in this," said one of the hosts.
At present in the UK, there are a number of NHS cancer screening programmes - for bowel, breast and cervical cancer - accessible for eligible individuals.
A new preventative initiative is also being gradually implemented for anyone at increased risk of contracting the disease, focusing on people of a certain age, who are smokers or were former smokers.
Individuals may request specific tests, but there is no national programme currently available.
The Stand Up to Cancer initiative, which has generated £113m since 2012, is supporting dozens of clinical trials encompassing 13,000 patients.
The Monarch, in a message for guests at a gathering for cancer charities in earlier this year, had spoken of understanding the "intimidating and at times scary situation" for cancer sufferers and their support networks.
But he stated his experience of living with cancer had demonstrated that "the most difficult times of disease can be illuminated by the support of carers," as he praised those who looked after individuals with the illness.
Royal representatives has not made public the nature of cancer the King has, or the therapies he has received. The King's cancer was identified after he had undergone a medical treatment.
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