The King is set to pause his cancer treatment during his tour of Australia and Samoa, according to reports.
The monarch, 75, and his wife Camilla will travel overseas from 18 to 26 October, first carrying out engagements Down Under before heading to Samoa for the Commonwealth Heads of Government Meeting (CHOGM).
Charles will continue with his ongoing treatment right up until he flies but his doctors are happy for it to be briefly stopped while he is away on his high-profile trip, the Daily Mail reports.
The treatment will then continue as soon as he returns to the UK.
The King was diagnosed with an undisclosed form of cancer in February, after receiving treatment for an enlarged prostate.
His daughter-in-law, the Princess of Wales, also recently completed chemotherapy after her own cancer diagnosis, which she revealed back in March.
© GettyCharles's programme during the long-haul visit is likely to be designed to afford him time to rest and recover from the many hours he will spend flying during his trip.
A Buckingham palace spokesman previously said: "We've had to, as you would with any visit, think about how you can ensure their Majesty's energies are preserved to be at their best."
He added: "There had been some hope earlier in the year for their Majesties to be able to visit New Zealand. On doctor’s advice, and in close consultation with the Australian and New Zealand governments, that wasn't able to take place. We've had to make some difficult decisions about the programme with the Australian government, about where their Majesties can get to."
© GettyHighlights of the Australian leg will see the royal couple spending time in the capital Canberra meeting leading figures and paying their respects to the country's fallen, while in western Sydney they will attend a community barbecue – a staple of Australian culture.
In Samoa, the programme will follow a similar theme to Australia with the King attending events around sustainability and biodiversity, while the Queen will focus on her interests of literacy and domestic violence and sexual abuse.
Charles and Camilla held a Commonwealth reception at St James's Palace last week, where the King was given a Samoan dance lesson.
