The Monarch has recorded a personal message concerning his experience with cancer, which will be broadcast as part of this year's Stand Up To Cancer campaign, organised by a leading cancer charity and a television broadcaster.
Official sources stated the King would discuss his "path to recovery" as a person living with the disease, in a televised statement on this Friday at 20:00 GMT.
The message, taped inside Clarence House two weeks ago, will emphasise the critical nature of routine screenings to ensure more people diagnose the illness at an initial point.
This constitutes a uncommon insight on the wellbeing of the Sovereign, who has been undergoing regular treatment since revealing his diagnosis in the start of 2024. Analysts suggest unlikely the King will specify his specific form of cancer.
The annual charity initiative each year generates donations for medical research and therapies and encourages people to get check-ups to increase the chances of an timely detection.
The King's candid approach about his illness, and his experience as a patient, has been designed to increase understanding and to encourage more people to get checked - and this will be taken a step further with this exceptional personal contribution.
Up until now the King's main approach to his cancer has been to maintain his duties, preserving a full diary alongside his ongoing course of therapy, and he seems not to have sought to be characterised by his diagnosis.
This year has seen the King, 77, undertaking several overseas trips, notably to Italy and Canada, and hosting the biggest number of foreign dignitaries to the UK for almost 40 years, which included the German president recently.
The upcoming Stand Up to Cancer broadcast on Channel 4, hosted by celebrities like Davina McCall, Adam Hills and Clare Balding, will urge people not to be frightened of getting health screenings.
Each presenter have been had experience with cancer - McCall said recently she had had an operation for a tumour, while Clare Balding was overcame thyroid cancer more than 15 years ago. Host Hills has previously mentioned his parent, who had stomach cancer and then later blood cancer.
The programme will appeal to the roughly nine million people in the UK who health organisations says are not current with national health programmes, with an digital tool to let people determine if they are eligible for screenings for key health indicators.
In an attempt to clarify screenings and show the value of early diagnosis there will be a real-time transmission from hospital departments at medical facilities in Cambridge.
"My aim is to remove the anxiety out of health checks and show everyone that they are not alone in this," commented one of the hosts.
At present in the UK, there are several key NHS cancer screening programmes - for bowel, breast and cervical cancer - available to eligible individuals.
A emerging preventative initiative is also being gradually implemented for people at high risk of being diagnosed with the disease, specifically targeting people aged 55-74 years old, who have a smoking history or were former smokers.
Men may enquire about prostate cancer checks, but there is not a universal scheme currently available.
The Stand Up to Cancer campaign, which has raised a significant sum over the past decade, is financing dozens of clinical trials with many patients.
King Charles, in a message for guests at a gathering for support groups in earlier this year, had referred to understanding the "daunting and at times scary experience" for patients and their support networks.
But he stated his experience of coping with cancer had shown him that "the darkest moments of sickness can be alleviated by the kindness of others," as he commended those who looked after cancer patients.
The Palace has not made public what kind of cancer the King has, or the therapies he has been given. The King's cancer was detected after he had undergone a prostate procedure.
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