Good day sir.i am 40 years,i had 2 ct scans of my colon lying up,down.i heard that my chances of having cancer age 55 to 60 is 100%.how true?was not told about the risks before the ct scan,i heard that i should have done colonoscopy instead thanks?

Your risk is very low but not zero. you can get an idea if you discuss with your X ray team. About the same radiation as flying from Lagos to San Francisco CA several times is my guess but will vary by machine and protocol used. If it were 100% we would not be doing CTs. As Yogi Berra said: It is difficult to make predictions. Especially about the future.

Two CT scans would not increase your risk of cancer by any appreciable extent, over your baseline risk. You can reduce your risk of cancer by adopting healthy habits: Eat a mostly vegetarian diet, avoid alcohol, tobacco and street drugs, avoid excessive exposure to sun, get HPV vaccine, exercise 30 minutes each day, drink enough water so your urine is mostly colorless.