DELFIA PSA Kitを用いての血清PSA測定と前立腺集団検診における応用

Abstract

前立腺特異抗原(PSA)を前立腺癌マス・スクリーニングのためDELFIA PSA Kitで測定した。全て質問紙(DRE), 直腸指診を済ませ, 前立腺の燐酸塩(PAP)を測って疑いの持たれたものに行った。カット・オフ値を2.89ng/mlとすると, マーカーとしての感受性・特異性・正確度はそれぞれ80.6%, 90.0%, 89.4%なので, カット・オフ値を3.0ng/mlとした。PAPの有意性はマス・スクリーニングでの被験者の前もって検査されたPAPと比較して行った。PAP濃度で不明であった触知可能の39例中28例で前立腺癌がPSA濃度で一致したので, 検出の感受性はPAPより良いといえる。しかし偽陽性がstage Bに30.3%と高かった。血清PSAは年齢・前立腺の大きさと共に多かった。また直腸内指診より超音波が前立腺の大きさの推定には適当であった

The significance of prostate specific antigen (PSA) measured by DELFIA PSA kit in the 1, 177 serum samples examined by mass screening for prostate cancer was evaluated. All subjects were examined by questionnaire, digital rectal examination (DRE) and prostatic acid phosphatase (PAP) and the subjects in whom prostate cancer was suspected from abnormal DRE and/or elevated PAP were recommended to receive the secondary screening for the presence of prostate cancer. All serum specimens used for this study were kept in our serum bank. The cut-off value was investigated between non-cancer subjects (diagnosed as normal, voiding disturbance or BPH) and prostate cancer patients. When the cut-off value was 2.89 ng/ml, the sensitivity, specificity and accuracy as prostate marker was 80.6%, 90.0% and 89.4%, respectively. Therefore, the cut-off value was determined as 3.0 ng/ml. The significance of PSA was retrospectively evaluated compared to PAP in the subjects examined by our mass screening. Twenty eight of the 39 palpable prostate cancers which could not be detected from the PAP level were detected from the PSA level, namely the sensitivity of the detection using the PSA level is more excellent than that using PAP. However, the false negative rate obtained using PSA was high (30.3%) in the patients with stage B disease. The relationship among serum PSA concentration, prostate size estimated by DRE and age was investigated. PSA was increased with age and prostate size. This estimation should be confirmed by using an ultrasonography because the prostate size obtained by DRE is inaccurate as compared with that obtained by ultrasonography.