hamsters and rats

Question
My 2 dwarf hamsters will be going to the baby sitter over the holidays while I am out of town. I am a little concerned because the sitter owns 2 rats. She plans to keep my hamsters and the rats in the same room (different cages of course). Occasionally she lets the rats out to roam around. Are the rats agile enough to break into my hamsters wire cage? Will the rats or the hamsters be stressed out by being in the same room where they can see one another?
Thank you

Answer
I had a prior roommate who had rats and hamsters housed in the same room and nobody was stressed. The rats wouldn't try to get to the hamsters (usually they don't much care to investigate cages off limits to them), however they are opportunists and I wouldn't ever trust them with the hamsters loose - but thats a given. They'll be ok :)