And yes, those edgy adults, claiming to be aware of death/mortality and accpeting, usually have created lightning rods in theire conciousness for these fears.
Like believe systems, that reroute this fear into believe of immortality, or in the atheist case a feeling of superiority for living your life to the max, while all those others do not. Those fully aware are in asylums
I had Hodgkin's Lymphoma many years ago, in my final follow up they said the radiation damage means there's a higher than normal chance I'd get some entirely different cancer later in life, but as to Hodgkin's there's no difference from the rest of the population. If I get Hodgkin's again it isn't because the treatment stopped working, it just means the same or similar freak DNA change happened. Like if I broke the same leg again.
Best of luck to her.