My Mighty Mouse, any thoughts?

http://www.the-scientist.com/?articles.view/articleNo/42470/title/My-Mighty-Mouse/

This article is quite interesting. It deals with mouses being used as test subjects for when there's a sick human that's been diagnosed with a tumor. The way that this process work is that the doctors would extract some tumor tissue and apply it to the mouse. After the mouse has fully developed the tumor tissue, the researchers would try multiple combinations of medicine and apply it to the mouse seeing if it would have any positive effects and reduce the tissue.

I strongly feel that this is great that it's helping the human kind but at the same time, the mouses are probably suffering from what the researchers are giving them. Do anyone think this is a sort of animal abuse as well?