You may not believe it now, but if you are diagnosed with cancer, you come to terms with it and then you get on with your life. You have to, and everyone finds their own way of doing so, but everyone does. It's this initial wait, when it's all new and a bit frightening, that's by far the most difficult part of the whole process. It may seem like an eternity until you get your final diagnosis (it may take a couple of months), but all you can do is try not to think "What if..." and just take things one day at a time.
All the best,
Chris