Should animal experimentation be permitted?

I think that if we can do experiments on humans in the name of good medicine then yes animals are a good source to learn from. I know that there are places and groups out there that would would want to get into a verbal or even physical altercation because of that statement, but I really don't care. If lets say that a cancer medicine, that in theory could cure cancer, was ready to be tested. Now we are unaware of the side effects that may occur. Well it seems that we have ran into a problem, how can we prove that this medicine actually works without harming a human life. The answer is easy, use animals.
Although I understand that these are also Gods creatures and that they should be harmed, but come on we are at the top of the food chain, testing experiments on animals, to within reason( I know that could go either way).