In an interview with Hello! magazine, Osbourne, 60, said:
As soon as I found out I had the breast cancer gene, I thought: 'The odds are not in my favour'.
I've had cancer before and I didn't want to live under that cloud: I decided to just take everything off, and had a double mastectomy.
More top news
The returns of Benedict Cumberbatch's detective and the X Factor judge were among 2014's most tweeted TV moments in a billion conversations.
A family has issued an appeal to help find their missing pet turkey - in case he gets gobbled up as someone's Christmas dinner.
The winner of X-Factor Ben Haenow has revealed how keen he is to have the Christmas number one.