Cut-off point of large prostate volume for the patients with benign prostatic hyperplasia

Abstract

Purpose: Prostate volume (PV) is a key predictor of both the progression and response to medical therapy for the patients suffering with benign prostatic hyperplasia (BPH). 5 alpha reductase inhibitors are effective for the patients with a large PV. Prostate-specific antigen (PSA) has been predominantly studied as a proxy marker to estimate the PV in a Caucasian patient population. If the PV of Korean men is smaller than that of Caucasian men, then the PSA-PV may be different for Korean men as compared with the other races. We evaluated the optimal PSA cut-off point to predict the response to 5 alpha reductase inhibitors with using Korean PSA-PV equations. Materials and methods: Patients aged between 50 and 79 years with lower urinary tract symptoms and BPH were enrolled in this multicenter study from 1999 to 2004. IPSS, PSA, uroflowmetry and TRUS measurements were performed on all the patients. We performed the computations using the logarithms of the PSA and PV. PV and PSA have an age-dependent log-linear relationship. The prediction curve was given by PV(55)=28.84× PSA0.208, PV(65)=30.36×PSA0.245, and PV(75)=30.23×PSA0.280. If a PV of 40ml was applied to these equations, then the PSA values were obtained for men in their 50s, 60s and 70s, respectively. If these PSA values were again applied to the Roehrborn's equations, then the PVs of Korean men were obtained. Receiver operating characteristic (ROC) curves were constructed to evaluate the ability of the serum PSA to predict the threshold PV in the men suffering with BPH. Results: The analysis included 5,716 patients with a mean age of 64.3 years, a mean baseline PV of 36.9ml and a baseline PSA value of 2.4ng/ml. The approximate cut-off PV for the Korean men was 35ml. The ROC curve analysis revealed that PSA had good predictive value for the PV cut-off point (35ml) from the Korean PSA-PV equations. The approximate age-specific criteria for detecting Korean men with a PV exceeding 35ml are a PSA >1.2ng/ml, >1.6ng/m, and >2.0ng/ml for the men with BPH who are in their 50s, 60s and 70s, respectively. Conclusions: The PSA-PV relationship in Korean men shows that Korean men have a lower PSA and a smaller PV than Caucasians. The PV of Korean men corresponding to a PV of 40ml for Caucasians was approximately 35ml.