Does free to total ratio of prostate-specific antigen alter decision-making on prostatic biopsy?

OBJECTIVES

For patients with prostate specific antigen (PSA) values of 4-10 ng/mL, some urologists perform prostatic biopsies depending upon the findings of digital rectal examination (DRE) and transrectal ultrasonography (TRUS), and others perform biopsies on most of these men regardless of the findings of DRE and TRUS. The purpose of this study was to examine whether the information given by the measurement of the ratio of free to total (F/T) PSA can alter decision-making on prostatic biopsy.

METHODS

One hundred and two (102) men with PSA values between 4 and 10 ng/mL, were included in this study. All men were examined with DRE and TRUS; a F/T PSA ratio was also measured, and six prostatic biopsies were taken from each patient.

RESULTS

In 102 men who were biopsied, 22 (21.5%) prostatic carcinomas were identified. Among these 22 cancer patients, 13 had abnormal findings in DRE and/or TRUS and would have been biopsied and diagnosed anyway. If we use only the F/T PSA ratio (cut-off value 0.20) to decide whom to biopsy, we would have diagnosed 16/22 cancers; the difference between these two procedures was not statistically significant (P = 0.17). If we decide to biopsy those patients who have abnormal findings in DRE and/or TRUS and those who have a F/T PSA ratio < 0.20, we would diagnose 20/22 cancers (P = 0.05) and at the same time, reduce the unnecessary biopsies from 80 to 41 (48%). With a PSA value between 4 and 10 ng/mL and no findings in DRE and TRUS and at the same time with a F/T PSA ratio > or = 0.20, we would have to perform biopsies in 20.5 men to find one cancer. On the other hand, in patients with suspicious findings in DRE and/or TRUS and a F/T PSA ratio < 0.20, in every two men that we biopsy we would find one cancer.

CONCLUSION

We believe that among patients with PSA values between 4 and 10 ng/mL after performing DRE and TRUS, the additional information of F/T PSA ratio can help since it increases the number of cancers detected and reduces the number of unnecessary biopsies.