Is free-to-total PSA ratio a useful predictor of prostate cancer?
The free-to-total PSA ratio is a useful predictor of prostate cancer. In 1997, it was approved by the United States Food and Drug Administration, showing that it is effective for that purpose and that it is safe. But it is more accurate in men whose total PSA values are between 4 and 10. But it is a less robust predictor in men who have PSA values between 2.5 and 4. Since there is a general tendency to use lower cut-off levels, we really need to have a marker that is better than the percent free-PSA for identifying men who are more likely to have prostate cancer and possibly avoiding more unnecessary biopsies. Question 4: What is pro-PSA? Pro-PSA is an isoform of PSA. It is similar to the situation with cholesterol. Initially we knew that there was total cholesterol. Now we know that there was high-density cholesterol and low-density cholesterol, so sort of good cholesterol and bad cholesterol. The same is true for PSA. Initially, we knew that PSA had two forms, free-PSA, which was fre
