Colon cancer- mother died at 80, granfather at 33....

My mother died of colon cancer at the age of 80. My grandfather died at the age of 33 of the same cancer. My doctor recommends that I have colonoscopy and gastroscopy. She tells me that I would have general anaesthesia and it is a very safe procedure. I would have to stay in hospital overnight. I am very scared to go ahead with this. I have heard some bad stories about this procedure going wrong. I am a very healthy (in all aspects), slim 52 years old woman. I think I should wait a few more years for this procedure. What do you think? Thank you very much for your advice.