Today we received the results and everything was negative! Although this doesn't explain the presence of my sarcoma, this is great news and means that I'm not at any elevated risk for developing any additional sarcomas or cancers for that matter. I have the same cancer risks as anyone else. It also means my parents/grandparents are off the hook for passing down bad genes.
As far as why I developed a sarcoma, my geneticist explained that either I just have bad luck or I developed the tumor based on environmental factors. Which brings me to my initial hypothesis: Diet Coke, McDonalds (minus their vanilla cones), artificial sugars and microwaves give you cancer! Watch Out!