The Daily Mail (U.K.) reports material from a Russian source called "General SVR Telegram" and calls the rumors "unconfirmed." The Daily Mail writes:
Vladimir Putin may be forced to give up control of the war in Ukraine for days as he is set for cancer surgery, a 'Kremlin insider' has claimed..
The Russian dictator will reportedly nominate hardline Security Council head and ex-FSB chief Nikolai Patrushev to take control of the invasion while he is under the knife.
He has reportedly delayed surgery, which will now not take place before the Victory Day commemoration of Russia's World War Two victory in Red Square on May 9.
This may mean something, or it may mean nothing. Rumors of Parkinsonism have followed Putin for some time, and the word "cancer" is associated with this surgery story. A variety of sources have commented that he does not look like a healthy person.
Let me add, I wish no one ill health, not even demonstrably bad persons of whom Putin appears to be one. I especially wish no ill health to anyone with a nuclear trigger to pull; such people need to be sharp mentally and have something to lose, for all our sakes.