I have to agree with what others are saying about cancer and breeding the parent dog. I do not think it was a very good idea. Just because the farther had cancer though doesn't mean that your dog will. For as far as training him , why not? He was sent away for training and some dogs will only respond well to the one/s that trained them. So perhaps after a while he will come around anyways.. I do not think that I would discourage trying to train him but try and keep it fun for you and the dog. Also remember that training takes time and when the attention of the dog leaves the training give him a break for a little while.. Good luck with what you decide..