Posey, you might know I'm being treated for breast cancer at the moment.
My advice would be, imagine the worst. What if you do develop it? You might. You might have to have surgery and chemo like your sister, and like me. It's not much fun, but I can still do lots of things on the days when I feel well, and I haven't given up living just yet. Even if you did develop it the chances are that you would be treated and survive and go on to live a normal life.
Then imagine even worse, what if it was terminal? What would you do? You would undergo treatment to help you live longer and feel better. You would use the time you had left to do what you wanted to do. And then you would die. Is that frightening? Perhaps it is. I don't think it's so bad to have lots of warning before you die. It gives you time to do and say things you want to do. I've had to give this a lot of thought over these four months since my diagnosis.
All of us, those with or without cancer, could suddenly drop dead of a heart attack or be run over, or murdered by a robber...or anything. Are you obsessing about all those things? They could happen to you too.
But the overwhelming likelihood is that you will live to be an old lady, be as grumpy as you like and die in your sleep. Worrying won't change the odds, or if it does it will worsen them.
Have your screening without fail, check for lumps, live a healthy life and have fun, lots of love, and lots of laughter. Then when your time comes you won't feel cheated, because you will have had a wonderful life.