前立腺癌腫瘍マーカーとしての前立腺特異抗原(PSA)の検討 : MARKIT-M PAによるPSA測定の臨床的意義

Abstract

PSAの新しい酵素免疫測定法キットであるMARKIT-M PAの感度は0.5 ng/ml, 検出範囲は0.5～100 ng/mlであった.MARKIT-M PAとMARKIT-F PAの両キットによる測定値はよく一致しており, 極めて高い相関性(r=0.987)が認められた.BPH(良性前立腺肥大症)群を陰性対照として用いた場合, BPH患者における上限カットオフ値は3.6 ng/mlと決定された.末治療前立腺癌患者48例中, 77%はMARKIT-M PAアッセイにより検出できた.BPH群を陰性対照として用いると, 特異性は93%, 診断効率は86%であった.直腸内触診直後に採血されたBPH患者27例では, 15%の症例でPSAが上昇していた.前立腺癌患者の追跡時, 臨床的に再燃と診断された11例中9例でPSAは異常高値を示した.臨床的に制癌と診断された15例では何れもPSAはカットオフ値内にあった

Serum prostate-specific antigen (PSA) levels in patients with prostate cancer and benign prostate hypertrophy (BPH) were investigated with a newly developed enzyme immunoassay (MARKIT-M PA, Dainippon Pharmaceutical Co. Ltd., Osaka, Japan). Sensitivity of the assay system is 0.5 ng/ml and the detection range is 0.5-100 ng/ml. There was a high linear correlation (r = 0.987) between the assay and MARKIT-F PA, and values obtained with the assay were almost equal to those yielded by MARKIT-F PA assay. Using the BPH group as a negative control, the upper cut-off value in BPH patients was determined to be 3.6 ng/ml. Of the 48 patients with untreated prostate cancer, 77% was detectable by means of MARKIT-M PA assay. Using the BPH group as a negative control, specificity and efficiency were 93% and 86%, respectively. In another group of 27 BPH patients whose blood samples were taken immediately after digital prostatic examination, PSA was elevated in 15%. During follow-up of prostate cancer patients, PSA was elevated in 82% at the time of clinically detectable progression. In 15 patients whose disease was clinically well controlled, all levels of PSA were observed to be negative. These findings suggests that detection of serum PSA with this assay is of great use both in the diagnosis and monitoring of prostate cancer patients.