Dr. Tewari, of the Dept. of Urology at New York-Presbyterian Hospital/Weill Cornell Medical Center, discusses the prostate cancer biopsy and its effectiveness. While it's the best they have, it is not perfect.

I think the prostate biopsy, while it is a great tool in diagnosing prostate cancer, is not perfect. Challenges are that, at any time, you can only put in twelve to twenty, thirty needle into a prostate. Sometimes needles miss an area where the cancer is because it's like poking into a pillow in which a couple of golf balls are hidden. And you cannot feel them, so you have to just be very lucky in hitting them. But it seems to be working, and that's the reason we are diagnosing so many prostate cancers. Having said that, biopsy is not very accurate at predicting how much of the cancer we are going to find when the prostate is removed. And there is a significant underestimation of the prostate cancer when we correlate between the biopsy and the actual picture.