> current over-the-counter NAD+-precursors have been shown in animal models to raise cellular NAD+ to dangerously high levels

Is this a problem with the molecule or the dose?

Uh... which one? Choice is not obvious to me, and I think it would depend on the type of cancer.

Except that time of death comes on average many years later for Alzheimer's than cancer. In the same thought, better die from heart attack instantly but unfortunately much earlier, which would be devastating for the relatives.