What I meant is, “cancer” mice are carefully bred / engineered to develop cancer. You can imagine their disease dynamics are very different from the normal popu

What I meant is, “cancer” mice are carefully bred / engineered to develop cancer. You can imagine their disease dynamics are very different from the normal population of mice who get cancer more rarely (and presumably are eaten first by something else). Whereas aging, you just let the mice get old. They have “real”, “natural” old age, not an artificial one.