Is it unreasonable to propose marriage to someone who is terminally ill?

So just to be clear , no gain for the asker and more than exstatic to proceed if she said Yes , and survived of course. The main idea would be to possibly extend her life , now this may still be unlikely , we had been together on and off , and I've known her for 20 plus years. I think she'd be really excited in a positive way , even if she said No , I think she'd really like to be able to say No ( if that makes sense ) . It's all about maybe continuing life , and she has always been extremely important to me , but she is very very sick ( cancer ) vastly younger than me , it seems so unfair.
What do you honestly think?
Updates
1 d
I'm still giving consideration to whether she is even well enough at this point , bcoz lots of cancer drugs involved.. So the idea would be pointless right now , so we will have to map progress.
Updates
14 h
She has now gained a blood transfusion, last time it didn't work ( blood attacked blood ) but for now a little more coherent which is at least good in short. When blood rejected Kemo was put on hold previously.
Is it unreasonable to propose marriage to someone who is terminally ill?
Post Opinion