The Monarch has filmed a first-hand account regarding his journey with cancer, set to air as part of this year's Stand Up To Cancer drive, run by Cancer Research UK and a major network.
Buckingham Palace confirmed the King would discuss his "healing process" as a cancer patient, in a televised statement on Friday at 20:00 GMT.
The message, filmed within his London residence recently, will highlight the critical nature of preventative health checks to help guarantee more people detect the illness at an early stage.
This will be a rare update on the wellbeing of the King, who has been in a course of therapy since revealing his diagnosis in the start of 2024. But it is thought unlikely the King will disclose his type of cancer.
The annual charity campaign each year generates donations for clinical trials and treatment and urges people to get screenings to boost the odds of an timely detection.
The King's public discussion about his health challenge, and his experience as a patient, has been aimed to promote education and to encourage more people to get screened - and this will be taken a step further with this unique royal involvement.
To date the King's key philosophy to his cancer has been to maintain his duties, maintaining a busy schedule alongside his frequent sessions of care, and he is understood not to have sought to be overshadowed by his diagnosis.
Recently has seen the Sovereign, undertaking several international tours, such as visits to Italy and Canada, and receiving the biggest number of inward state visits to the UK for almost 40 years, featuring the German president last week.
The upcoming Stand Up to Cancer broadcast on television, hosted by celebrities including Davina McCall, Adam Hills and Clare Balding, will encourage people not to be scared of getting health screenings.
All three have been had experience with cancer - McCall disclosed in November she had had an operation for a tumour, while Balding was treated for thyroid cancer over a decade ago. Presenter Adam Hills has previously spoken about his late father, who had stomach cancer and then later another illness.
The broadcast will reach out to the approximate nine million people in the UK who health organisations estimate are not compliant with NHS screening schemes, with an website to let people see if they are eligible for screenings for several common cancers.
In an bid to explain screenings and demonstrate the benefit of timely identification there will be a real-time transmission from cancer clinics at two Cambridge hospitals in Cambridge.
"I want to remove the anxiety from cancer screening and prove the public that they are not on their own in this," said one of the hosts.
Right now in the UK, there are several key national health screening services - for bowel, breast and cervical cancer - available to eligible individuals.
A new scheme for lung health is also being phased in for people at potential risk of being diagnosed with the condition, focusing on people in a specific age bracket, who have a smoking history or have smoked in the past.
Individuals may request prostate screenings, but there is not a universal scheme operational.
The Stand Up to Cancer campaign, which has raised £113m for many years, is funding multiple medical projects encompassing 13,000 patients.
His Majesty, in a statement for attendees at a event for cancer charities in April, had spoken of recognising the "overwhelming and at times scary experience" for those diagnosed and their loved ones.
But he stated his first-hand encounter of coping with cancer had demonstrated that "the darkest moments of sickness can be alleviated by the kindness of others," as he thanked those who looked after cancer patients.
Official sources has not revealed the nature of cancer the King has, or the therapies he has undergone. The King's cancer was discovered after he had received a routine operation.
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