Welcome to the forums! Sending you hugs if you accept :hug:
Cancer sounds terrifying to get through, and I'm guessing possibility exists, many have gotten PTSD from surgeries and similar.
I am a sufferer, and I can say that what you should be doing varies. A hug is often helpful, but still, depends. My supporter often says that she doesn't know what to do... Neither do I, but mostly we can craft up something that works!
There are much more experienced members that can give meaninful advice, but options come to you.
Interesting thing comes when both are sufferers, and it's something that many have opinions on, better or worse, all depends on situation. Aiming for understanding or safety?
As Laurie said, this forum is quite resourceful and a lot of knowledge can be found here.
Well, good luck and hopefully this place helps you!