DELFIA PSAを用いた血清PSA測定の臨床的意義

Abstract

DELFIA PSAの臨床的検討を2施設の共同研究で行った.本法はeuropiumをtracerとしたtime-resolved fluoroimmunoassayであり, 0.10～500 ng/mlという3.5 logにおよぶ広い測定範囲を有しており, 検体必要量も25 μlと少量で済み, 再現性にも優れ, さらに自動化も可能であった.また, 本法はTander-R PSAと同一のPSA値となることも特色である.健常男性227例の血清PSA値の平均+3S.D.から, 1.98 ng/mlを正常上限値と決定した.一方, 前立腺癌とBPHを鑑別するもっとも効率的なcutt-off値として, BPH症例の平均+S.D.値である11.7 ng/mlが優れていた.さらに, 前立腺癌症例のフォローアップにおける有用性はきわめて高いことが確認できた

Serum prostate specific antigen (PSA) values detected by DELFIA PSA were evaluated for usefulness in the diagnosis and follow-up of patients with prostate cancer. The system is time-resolved fluoroimmunoassay using europium as a tracer, which has a detectable range of 0.10-500 ng/ml with a small sample volume (25 microliters) and reliable quality control data. Furthermore, serum PSA values detected by the assay were equivocal to those detected by Tandem-R PSA. From the mean +3 S.D. of serum PSA values obtained on 227 normal males, 1.98 ng/ml was decided as an upper normal level. Serum PSA values in benign prostatic hyperplasia (BPH) (n = 69) and prostate cancer (n = 86) patients were statistically higher than those in normal males. However, when 1.98 ng/ml was used as a cut-off value, the false positive rate in BPH cases elevated up to 80%. Therefore, in the differential diagnosis of prostate cancer and BPH, we recommend 11.7 ng/ml (mean + S.D. in BPH cases) as a cut-off value, in which sensitivity is 72.1%, 88.4% are true negative in BPH, and efficacy is 79.4%. Serially determined serum PSA values in following up the patients with prostate cancer were confirmed to be highly effective for diagnosing recurrence and evaluating treatment responses. These findings suggest that DELFIA PSA is a useful tool for determination of serum PSA values.