dzzzd12 - confront your friend, gently, tell her you are suspect of her having cancer, ask her why she lied about it, but try not to be angry with her when you do it. you are obviously a caring person and love your friend very much, confronting her is the only way you can cut off the lies!
it sounds like she lied for a reason, perhaps the need for attention, but, you should let her know she doesn't have to do that for attention from you.
if you let it go she may get worse and start lying more often. it is going to be difficult, but, you will be helping her in the long run don't you think? I have a very good friend who did just those sorts of things for me ad without her I would have never have made the changes necessary to reform my compulsive lying for good.
of course these are just suggestions! Either way it is going to be a friendship testing situation!