When I was 2 years old I had a painful, swollen knee that wouldn't get better. The doctors thought I had bone cancer and wanted to amputate my leg. (This was around the same time that one of the Kennedy kids had bone cancer, so doctors were very aware of it.) My parents asked them to biopsy first. It was found that I had juvenile rheumatoid arthritis, not cancer. So I got to keep my leg. To this day, whenever I run, ski, whatever, I'm thankful for my parents insistence and that the original diagnosis was false.

On the other hand, my sister has a genetically based breast cancer. So I will continue to get mammograms (and Paps, etc.). My chance of getting breast cancer from my genes is much higher than the chance that the radiation from the mammograms will cause me to get cancer. For me, the risk is far outweighed by the benefit.