I recently lost someone dear to me to ovarian cancer. It was indeed so painful. When I think about the pains and the number of chemotherapy she went through, it only breaks my heart. she was strong and always cheerful. When the drug addiction to pain killers (morphine) started, I knew you just wanted to stay. Its always sad to say goodbye.
Here's a poem from 
Title : Letter to a dying loved one
God saw you getting tired
And a cure was not to be
So he put his arm around you
And whispered come with me.....
I sat beside your bedside
As I watched you fade away.........
In tears I watched you sinking
My heart was breaking..........
A golden heart stopped beating
God broke my heart to prove to me
He only takes the best
You told me never to leave you
So I hold you tightly within my heart
And there you would remain................