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 between patients with benign and malignant histologic findings. Methods: The concentration of total and free PSA and the F/T ratio were determined in 35 men before and Ih after prostatic biopsy. The level of PSA was 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, there 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 biopsies revealed no prostate cancer. In patients with stage B cancer, these parameters increased more than those with stage C/D cancer. Conclusion: Prostatic biopsy causes a dramatic increase in total and free PSA. The F/T ratio also increased after biopsy. The PSA response to prostatic biopsy might be different in patients with and without prostatic malignancy The response might also be different according to stage of prostate cancer.