Prostate specific antigen density for discriminating prostate cancer from benign prostatic hyperplasia in the gray zone of prostate-specific antigen

Abstract

PSA density(PSAD)組織学的に診断された前立腺肥大症(BPH)63例と前立腺癌(PC)234例のうち, PSAがgray zoneを呈するBPH36例とPC25例を対象とした.PSA値はMarkit-F又はMPAで測定しStanford reference valueを従い換算した.PSAD値はPSA値/前立腺体積で計算した.PSA値はBPHで6.42±1.80, PCで7.80±2.15となり, BPHとの間をp=0.0116の有意差を認めた.前立腺体積はBPHで33.4±14.1, PCで17.1±8.2となり, BPHとの間にp<0.0001の有意差を認めた.一方PSAD値はBPHで0.218±0.085, PCで0.576±0.363となりBPHとの間にp=0.0001の有意差を認めた.PSAD及び前立腺体積のcut-off値を各々の0.218, 30mlとした場合, 90%以上の感度を維持しながら特異性は共に56%と良好な結果が得られた

Serum prostate specific antigen (PSA) is currently the best blood marker for prostate cancer. However, low specificity for detection of prostate cancer, especially in the gray zone of PSA, is a problem. We evaluated the clinical significance of PSA density (PSAD) in gray zone PSA cases with conversion of serum PSA to a Stanford reference value. In a series of histologically confirmed 63 benign prostatic hyperplasia (BPH) patients and 234 prostate cancer patients, 36 BPH patients and 25 prostate cancer patients had gray zone PSA levels. Serum PSA was measured with the Markit-F or Markit-M PA assay. All data were converted to Stanford reference values. We used transabdominal ultrasound to determine prostate volume. PSAD was determined as the serum PSA/prostate volume ratio. The mean PSA values for BPH and prostate cancer were 6.42 +/- 1.80 and 7.80 +/- 2.15 ng/ml (p = 0.0116), respectively, and prostate volume was 33.4 +/- 14.1 ml and 17.1 +/- 8.2 ml, respectively (p 90% were 0.218 for PSAD and 30 ml for prostate volume. At these cut-off values, specificity reached 56% for each marker. In discriminating prostate cancer from BPH in the gray zone of PSA, PSAD demonstrated better performance than PSA.