Royal doctors gave Charles, 75, permission to briefly halt the weekly cycle in order to fly around the world for his key visit next visit, followed by a state visit to Samoa in the South Pacific.
The monarch, who was diagnosed with an undisclosed form of the disease in February, will receive treatment up until his departure, and resume the outpatient appointments when he returns to the UK, the Daily Mail reported on Monday.
This will be the couple's first trip to Australia since King Charles became head of state. (AP PHOTO)
He will be away for 11 days, with the tour covering nine days with two days of travel either side, and his entourage will include, as is usual for Charles's official overseas visits, his doctor.
The long-haul trip with the Queen is a major milestone for the King.
It will be his most significant overseas tour since his cancer diagnosis and his first to Australia as the nation's head of state, looking set to prompt debate about the future of the monarchy in the country and whether it should become a republic.
Australian retired football player and human rights activist Craig Foster revealed he has turned down an invitation to a community barbecue with the King and Camilla.
The ex-Socceroo, who is the former co-chairman of the Australian Republic Movement, thanked New South Wales premier Chris Minns for inviting him, but rejected the place.
He posted on X: "No thanks. I look forward to being 'in the presence of' our first Aussie head of state.
"When we put our big pants on, as a country."
Thanks Anna and — Craig Foster (@Craig_Foster) @ChrisMinnsMP But, no thanks.I look forward to being 'in the presence of' our first Aussie Head of State.When we put our big pants on, as a country. pic.twitter.com/hE08NpM0SZOctober 4, 2024
Meanwhile, Graham Smith, chief executive of the UK anti-monarchist organisation Republic, revealed he has travelled to Australia, ready to stage events and protests in Sydney and Canberra during the tour.
Australia's prime minister Anthony Albanese has a long-held aim of holding a referendum on breaking ties with the British monarchy and his country becoming a republic.
The plans were put on hold after Australians overwhelmingly rejected a plan to give greater political rights to Indigenous people in a referendum held last year.
Charles and Camilla arrive in Australia on October 18 and the trip will see them meet locals and tuck into produce at the community barbecue - a staple of Australian culture - in western Sydney.
They will also be officially welcomed by Mr Albanese in Canberra, meet two Australian professors hailed for their pivotal research on melanoma skin cancer and review the Australian naval fleet in Sydney Harbour.
The program of engagements has been designed to give the King time to rest and recover from the many hours he will spend flying during his trip.
After the Australian leg, Charles will attend events in Samoa looking at sustainability and biodiversity, while the Queen will focus on her interests of literacy and domestic violence and sexual abuse.
The King will then gather with world leaders in Samoa's capital and only city Apia for his first Commonwealth Heads of Government Meeting (CHOGM) since he became monarch and head of the Commonwealth.
Camilla is reported to be arranging a pre-tour break with friends this week while Charles is spending most of his time in Scotland to conserve his energy ready for his travels.
Buckingham Palace declined to comment.
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