Whether or not you'll someday get cancer or any disease can feel like a roll of hundreds of dice. Calculating the odds -- and knowing what they mean -- is tricky. Katie Harbath/Flickr hide caption toggle caption Katie Harbath/Flickr Shots - Health News What's My Real Cancer Risk? When Online Calculators Don't Compute August 18, 2013 There's a difference between knowing your breast cancer risk and believing it. When psychologists asked several hundred women to plug personal health data into an online tool that then calculated their breast cancer risk, nearly 20 percent rejected their scores as wrong.