Prostate specific antigen(PSA)軽度上昇症例の前立腺癌診断におけるPSA densityの有用性

Abstract

泌尿器科において施行された前立腺生検及びTUR-Pの病理結果をもとに, PSA軽度上昇症例におけるPSADの前立腺癌鑑別診断能を検討した. 1)各検査法の診断能を比べるとsensitivity, PPVはPSA(cut off値4.5 ng/ml)82%, 38%, 直腸診+TRUS 73%, 39%, PSAD(cut off 0.13) 91%, 61%であり, PSADを用いることにより, 癌陽性率の低いPSA軽度上昇域の症例に対しPPVが著明に向上した. 2)直腸診, TRUSに異常所見の得られなかった57例中6例に癌症例を認めたが, この症例群に対してもPSADはsensitivity 83%, specificity 82%, PPV 36%, NPV 98%と高い癌検出力を認めた

The efficacy of prostate specific antigen density (PSAD) in diagnosing prostate cancer was assessed in 98 patients with serum prostate specific antigen (PSA) levels between 2 and 10 ng/ml who had a pathological diagnosis made by prostate biopsy or transurethral resection of the prostate. Of the 98 patients, 22 (22%) had prostate cancer. The PSA (based on a cut-off value of 4.5 ng/ml) had a sensitivity and positive predictive value (PPV) of 82% and 38%, respectively, for diagnosing prostate cancer, while the results for PSAD (based on a cut-off value of 0.13) were 91% and 61%. The PSAD was more efficient than the PSA levels and was also superior to digital rectal examination (DRE) combined with transrectal ultrasonography (TRUS), for which the sensitivity and PPV were 73% and 39%, respectively. Six (11%) out of 57 patients who were normal on DRE and TRUS had prostate cancer. In these 57 patients, the PSA (cut-off value: 4.5 ng/ml) had a sensitivity of 50% and PPV while the values for PSAD (cut-off value: 0.13) were 83% and 36% respectively. The PSAD could effectively detect even impalpable prostate cancer not visible on TRUS.