OP, I wish you the best. It's important to not think negatively, and to always think with hope...whatever the diagnosis may be...As the poster above says, this is easier said than done.
You are young, seem to be, otherwise, in good health, and that will stand you in good stead. If it's just on one, there's a good chance that you've caught it, whatever it may be...early, so that would seem to be a plus.
I'm just trying to refer to my Mother's diagnosis of her Breast Cancer...in this response...and treatment of various cancers has come along so far, and there's new developments everyday. Still work to be done, of course, but it's come a long so far. Organizations such as Macmillan provide outstanding information.