I need some advice and insight, please.

My coworker friend told me last week she was just diagnosed with stage IV cancer. I'm absolutely heart-broken over it, and I really want to help in some way but my hands are sort of tied. You see, she and I have same role in our big company but she works for a whole different business group and reports into a different reporting line. Our worlds somewhat touch but by not much. We've become friendly because she was my mentor when I first started here and was very generous with her knowledge and generally showing me the ropes. We've only met in once in person because she's located in an office many states away, but we talk on the phone one or two times a month and always go to each other when we're stumped by a work related problem.

I've exchanged some lengthy emails with her and urged her to call my personal cell or write to my personal email, if she wanted to talk offline. Beyond that, that's all I can really offer. I really want to help take some work off her plate, but due to our structure and other issues my boss says I can't really do that.

So, basically all I've left with is to repeatedly offer my ear and to check-in once a week or so. But what else can I say? What is soothing? I have no experience with sick friends/family members who has a long battle ahead of them.