Effect of prostatic biopsy on free-to-total prostate-specific antigen ratio in patients with prostate cancer

Background: We determined the effect of prostatic biopsy on the changes in total and free prostate-specific antigen (PSA) and free-to-total PSA ratio (F/T ratio) and examined if there are differences in these parameters betwe en patients with benign and malignant histologic findings. Methods: The concentration of total and free PSA and the F/T ratio were det ermined in 35 men before and Ih after prostatic biopsy. The level of PSA wa s measured with a chemiluminescent enzyme assay. Of 35 patients, nine were diagnosed as having prostate cancer. Results: In patients whose biopsy revealed cancer, the F/T ratio was lower than those without cancer, although there were no differences in total and free PSA value before prostatic biopsy. One hour after prostatic biopsy, th ere was an increase in the level of total and free PSA and the F/T ratio in all men. The increase in the F/T ratio was greater in patients whose biops ies revealed no prostate cancer. In patients with stage B cancer, these par ameters increased more than those with stage C/D cancer. Conclusion: Prostatic biopsy causes a dramatic increase in total and free P SA. The F/T ratio also increased after biopsy. The PSA response to prostati c biopsy might be different in patients with and without prostatic malignan cy The response might also be different according to stage of prostate canc er.