King Charles has been putting on a brave face while battling cancer which could spread to his other organs, a source has revealed.

Even though the monarch’s cancer was caught early, insiders claim that there are fears his condition could get worse, In Touch Weekly reported.

They said, “Although word is the cancer was caught early, there’s concern it could turn into something worse and possibly spread to other organs, which could be a death sentence.”

While King Charles appears healthy during his public appearances, the source said, “How he feels behind the scenes is another thing,” adding, “Of course he must be worried.”

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The royal insider went on to add that “the Firm is preparing for the worst,” as they are working on updating plans for his funeral, called “Operation Menai Bridge.”

“Charles understands that it’s the expected thing to do, as he’s the king,” the insider said, revealing that he is doing everything in his power to “prolong his reign.”

Ingrid Seward revealed in her royal biography, titled My Mother and I, that Charles has a oxygen tent that he sleeps in to boost his health.

She claimed that the monarchy is suffering from short term memory loss and keeps a notebook to note down important details.