(((((((((((littlemissjess))))))))))))))
I just recently lost my aunt due to cancer. It's not nice
What you mostly want to do is acknowledge the person - the person owns the problem, the problem doesn't "control" the person. Just ignoring it won't work either, but just saying "I'm sorry you're going through so much right now" would help.
I hope her surgery goes well. Hugs and good thoughts to you all.