When I was 17, I found a lump in my breast and I was TERRIFIED. Even though the doctor told me it was probably benign, I had to have surgery and was horribly anxious till the results came back. Turned out to be just a fibrous cyst, but the chances of having another one are pretty high, and given the fact that I'm getting older I'm terrified of either finding another one and having to worry that it's cancer, or having one mask an actual cancerous lump.
A lot of people have to go through this, and the bottom line is that it sucks. Just try to keep on an even keel and not worry about something you can't prevent or control. Try to be present in the moment and enjoy what your doing for its own sake. If you find yourself fixated on the "what if's" of the situation, find a sympathetic ear to vent to. Take care of yourself, and know that we're here for you.