Peto's paradox - and the existence of whales in particular.
If cancer really is an inevitability, then whales, who have both livespan limits longer than that of humans, and enormous bodies with a staggering amount of living cells, would be full of cancer. They aren't.
Clearly, humans must have better innate cancer suppression than mice, and whales must have better innate cancer suppression than humans.
There are some hints that this may come down to programmed cell death and DNA repair mechanisms (i.e. the p53 pathway) more than the immune system tweaks - with immune response being the "last resort" of cancer suppression. But we also don't know enough about the immune system to be able to examine it the same detail we can examine the DNA repair pathways.
If cancer really is an inevitability, then whales, who have both livespan limits longer than that of humans, and enormous bodies with a staggering amount of living cells, would be full of cancer. They aren't.
Clearly, humans must have better innate cancer suppression than mice, and whales must have better innate cancer suppression than humans.
There are some hints that this may come down to programmed cell death and DNA repair mechanisms (i.e. the p53 pathway) more than the immune system tweaks - with immune response being the "last resort" of cancer suppression. But we also don't know enough about the immune system to be able to examine it the same detail we can examine the DNA repair pathways.