Hi needachat, sorry to hear about your friend. I am 42 was diagnosed with Stage 4 Bowel Cancer in October last year. Everyone is different but for me I wanted people to talk about the "elephant" in the room. Nothing anyone says can be worse than the doctor telling you that you have cancer. For me the worst thing was what I call the "cancer face" , the sad face like I was already dead.
My best friend became a rock for me. He was the guy who I could say anything to - no matter how morbid it was! Things I couldn't tell my wife or family. He didn't pity me or judge me and we laughed and joked about what I was going through.
I still remember the day when we out having a walk he said " Mate, we have been friends since we have been 12. It really sucks what is going on but you know what ever happens I will be by your side. Your children will be taken care of so if it all goes bad. If you want to howl at the moon I will be right beside you howling".
The thing is you can't take away your friend's pain but you need to the one person who doesn't care they have cancer and treat her like you normally would. Tell her you love her
Laugh together and cry together and everything in between
I hope this helps.