Well I do know that stress and anxiety isn't GOOD for our health. Not sure if it can increase our risk for cancer though. I did the same as you. I had this odd spot on my breast, I had read about inflammatory breast cancer, and thought for sure I had it. I saw a few different doctors. Some told me it was a skin thing, completely benign. Some told me it was a cyst. I did a mamogram and an ultrasound. They felt it was indeed a cyst. But that wasn't good enough for me and my health anxiety. I had my general surgeon remove it. It ended up being a benign skin tumor (dermatofibroma to be exact). I am glad that I did it, better to know then drive myself crazy wondering. But now with medication and a lot of positive thinking, I usually can get over something without going to extremes. It's a battle though!
Diagnosed with Crohn's Disease 2/06, and Health Anxiety/OCD 12/08 Taking Asacol, Questran, Toprol XL, and Celexa.