They exist in the UK and Canada where they will deny treatments for similar reasons or if deemed too expensive.
(edit:
I found a speech by Stephen Hawking on the matter:
https://www.hawking.org.uk/in-words/speeches/speech-1
Quick summary: At the start of the speech he refutes a claim that death panels exist in the UK NHS and that they would have let him die. Of course the strongest refutation is the fact that he was at the time -in fact- quite alive; thanks to the NHS.
)
It’s not disputed nor unknown that a variety of expensive/newer cancer treatments are not payed for by the NHS. I posted one example but there are many