What does all this mean?

I was just wondering what some of this info. means. My MIL has cancer.  They removed her female organs but then found it also in other places. Recently they felt some enlarged lymp nodes.  So I'm not exactly sure what kind of cancer she has.   She said its stage IV primary peritoneal/adenocarsoma (sp?)  what exactly is that?  And they also told her that her cancer in NOT curable but treatable. Is that because of the stage its in or maybe the kind?  And also what's the outlook for someone with this?  I can't find info. on this anywhere.  Thanks