The Monarch has filmed a intimate address regarding his battle with cancer, scheduled for transmission as part of this year's fundraising drive, organised by a leading cancer charity and Channel 4.
Official sources stated the King would reflect on his "healing process" as a individual battling cancer, in a video message on this Friday at 8pm UK time.
The message, filmed within his London residence two weeks ago, will highlight the vital significance of cancer screening checks to ensure more people catch the disease at an initial point.
This represents a rare update on the wellbeing of the Sovereign, who has been in a course of therapy since his condition was announced in early last year. But it is thought improbable the King will identify his specific form of cancer.
The awareness initiative each year generates donations for medical research and therapies and encourages people to get check-ups to increase the chances of an early diagnosis.
The King's relative openness about his health challenge, and his experience as a patient, has been intended to raise awareness and to persuade more people to get screened - and this will be advanced with this exceptional direct participation.
So far the King's main approach to his cancer has been to maintain his duties, maintaining a full diary in spite of his ongoing course of treatment, and he is understood not to have desired to be characterised by his condition.
Recently has seen the Sovereign, undertaking several foreign visits, notably to Italy and Canada, and receiving the biggest number of inward state visits to the UK for almost 40 years, featuring the German president in recent days.
This Friday's charity broadcast on television, hosted by presenters including several TV personalities, will appeal to people not to be afraid of getting preventative tests.
The hosts have been had experience with cancer - one host revealed in November she had undergone surgery for breast cancer, while Clare Balding was treated for thyroid cancer in the past. Presenter Hills has previously discussed his parent, who had one form of cancer and then later leukaemia.
The programme will appeal to the estimated 9m people in the UK who Cancer Research UK estimate are not up to date with NHS screening schemes, with an online checker to let people see if they are eligible for screenings for breast, bowel and cervical cancer.
In an bid to clarify cancer checks and illustrate the value of timely identification there will be a direct feed from cancer clinics at Addenbrooke's and Royal Papworth hospitals in Cambridge.
"The goal is to take the fear out of health checks and demonstrate everyone that they are not alone in this," stated a presenter.
At present in the UK, there are three NHS cancer screening programmes - for major health concerns - accessible for certain age groups.
A recently launched lung cancer screening programme is also being slowly rolled out for anyone at increased risk of contracting the condition, focusing on people in a specific age bracket, who are smokers or used to.
Men may discuss 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.
The Monarch, in a message for guests at a gathering for related organisations in April, had referred to acknowledging the "overwhelming and at times frightening experience" for those diagnosed and their support networks.
But he noted his experience of living with cancer had demonstrated that "the most difficult times of sickness can be alleviated by the greatest compassion," as he thanked those who cared for individuals with the illness.
Official sources has not made public what kind of cancer the King has, or the therapies he has received. The King's cancer was discovered following he had had a medical treatment.