The Efficacy of Prostate Specific Antigen adjusted for the Transition Zone Voume (PSATZ) as a New Predictor of Prostatic Cancer / 대한비뇨기과학회지

ABSTRACT

PURPOSE: Although PSA(prostate specific antigen) is an excellent tumor marker, it is not prostate cancer-specific but organ-specific. The objective of this study is to assess the efficacy of prostate specific antigen adjusted for the transition zone voume(PSATZ) in diagnosing prostate cancer in men with intermediate PSA levels of 4.1 to 10.0 ng/ml. MATERIALS AND METHODS: Between March 1997 and September 1998, PSATZ was obtained from 67 patients who underwent ultrasound-guided systemic sextant biopsies and had a PSA of 4.1-10.0ng/ml. PSATZ was compared with PSA, PSAD(PSA density) and free-to-total PSA ratio(F/T ratio) via receiver operating characteristic(ROC) curves. RESULTS: Of 67 patients, 22(32.8%) had prostate cancer and 45(67.2%) had benign prostatic hyperplasia on pathologic examination. Mean PSA, F/T ratio, PSAD and PSATZ were 7.96+/-2.01ng/ml 0.10+/-0.06, 0.28+/-0.14ng/ml/cc and 0.70+/-0.28ng/ml/cc in patients with prostate cancer and 6.39+/-1.68ng/ml, 0.15+/-0.05, 0.16+/-0.06ng/ml/cc and 0.29+/-0.11ng/ml/cc in patients with benign prostatic hyperplasia, respectively. ROC curve analysis demonstrated that PSATZ, F/T ratio and PSAD predicted the biopsy outcome significantly better than PSA in all 67 patients(p<0.01, respectively). In a subset of 45 men with normal digital rectal examination, PSATZ predicted the biopsy outcome better than PSAD or F/T ratio significantly(p<0.01, respectively). With cutoff value of 0.35ng/ml/cc, PSATZ had a sensitivity of 86% and a specificity of 89% for predicting prostate cancer. With cutoff value of 0.12, F/T ratio had a sensitivity of 73% and a specificity of 71% for predicting prostate cancer. CONCLUSIONS: These results suggest that PSATZ is more specific and more accurate than PSA, PSAD or F/T ratio in distinguishing benign prostatic disease from prostatic cancer in men with intermediate PSA levels of 4.1 to 10 ng/ml. But large prospective studies are requested to assess the precise role of PSATZ in early prostate cancer detection.