BERKELEY, CA (UroToday.com) - PSA is one of the most important biomarkers for detecting prostate cancer and guiding decisions to biopsies of the prostate. Despite its adequate sensitivity, the use of PSA testing is limited by a significant lack of specificity, which can result in unnecessary biopsies. Use of the f/t PSA ratio has been shown to improve specificity in detection of prostate cancer. No definitive data are available indicating the optimal %f/tPSA that should be applied. Some controversy exists regarding the clinical benefits of f/t PSA because the large overlap between prostate cancer and benign disease for various f/t PSA cutoff levels provides conflicting data for the correlation between f/t PSA and a pathologic outcome.
Age-specific reference rates have been proposed as a means of improving specificity and positive predictive value of the total PSA in screening for prostate cancer. Previous studies demonstrated that the total PSA level is significantly related to age; however, an age-specific f/t PSA ratio has not yet been determined.
We investigated an optimal cutoff level of free/total PSA ratios (f/t PSA) in predicting prostate cancer in different age groups, focusing on the avoidance of unnecessary prostate biopsies. A total of 4 955 men were enrolled into the study. Serum tPSA, fPSA, and f/t PSA ratios were determined for the study population. Receiver operating characteristic (ROC) curves for each group were generated by plotting the sensitivity versus 1-specificity for the f/t PSA ratio.
This study shows that the use of f/t PSA ratio in patients with PSA levels of 4 -10 ng/mL should enhance the specificity of PSA screening and decrease the number of unnecessary biopsies. Ten percent (10%) f/t PSA ratio had the highest specificity with PLR and 30% f/t PSA ratio had the highest sensitivity and a lower NLR in all the age categories. According to sensitivity and specificity, f/t% PSA cutoff points were determined to be 10%, 15%, 15%, 10% in age categories 50-59 years, 60-69 years, >70 years, and all ages categories in patients with initial PSA level of 4-10 ng/mL. Our data are based almost entirely on Turkish men, not accounting for racial variability. The omission of race may limit the applicability of our findings. Another limitation is a lack of data about prostate volumes, of which concomitant BPH in large prostates may influence the f/t PSA.
The choice of the best cutoff for the f/t PSA ratio depends on a variety of arguments that mainly include the combination of screening modalities used. The age-related changes warrant further investigations in a larger, multi-centric and multi-national population to improve the clinical use of f/t PSA cutoffs.
Bulent Erol, MD as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.
Bulent Erol is an Associate Professor of the Department of Urology at Istanbul Medeniyet University.
He graduated from Istanbul University of Cerrahpasa Medical School and trained in Urology at the Istanbul University of Istanbul Medical Faculty. He worked as a staff urologist at Istanbul American Hospital and spent 6 years as an assistant professor of urology in Bulent Ecevit University in Zonguldak, Turkey.
Dr. Erol has published more than 60 papers in international urology journals. His main interests are male and female sexual dysfunction, male infertility, interstitial cystitis, and chronic pelvic pain syndrome. He has presented in different international meetings and moderated many urological sessions.
The cutoff level of free/total prostate specific antigen (f/t PSA) ratios in the diagnosis of prostate cancer: A validation study on a Turkish patient population in different age categories - Abstract