Humans aren't the only mammals that get cancer. Cancer is basically just an uncontrollable burst of cells dividing and blocking the functions of those cells around them. <-- (WAY oversimplification)
Different Cancers generally behave in the same manner, even cross-species. Therefore, this research could also benefit veterinary medicine as well.
Testing on mice and rats provides a faster view of what the various treatments do because of the increased metabolism in both these types of animal which makes the treatment run its course a lot faster than it would in humans. If one mouse dies, the other mice around it do not grieve and wail or alter their behavior in the least. In fact, a lot of times, the other mice will eat the dead one. When a human dies, the entire community feels the loss.
