Aspirin Reduces Risk of Cancer

I recently heard on a radio station that taking an aspirin can reduce the risk of getting cancer.  I was curious to know more about this so I looked it up online.  The cite I viewed stated that taking an aspirin daily will reduce the risk of colon, lung, and prostate cancer. Test were ran on both men and women and after taking spirin for three days the patients risk of cancer was reduced by 25 percent. Plan on looking further into this to see what does the aspirin contain that reduces cancer. I know some illnesses are hereditary. I wonder if it is inherited will the aspirin still be effective in reducing the risk of getting cancer?