前立腺特異抗原Tandem-RとMarkit-Mの臨床的有用性の比較検討

Abstract

前立腺癌患者と非癌患者の血清PSA値の間には両キットとも有意差がみられた.PSAの低濃度域におけるTandem-R PSA(TR)とMarkit-M PA(MM)との相関係数は0.68であり, 強い相関がみられなかった.臨床で用いているMMのcut-off値では, 限局性癌18例のうち15例と病期Cの24例中4例が診断されないという結果であった.換算式を用いて換算したMM値が4.0ng/ml以下を示した15例のうち4例が前立腺癌であった.ROC曲線下のTRとMMの診断能に差がなかったが, 低濃度域でのMMからTRへの変換式に問題点を含んでいた

The Tandem-R PSA (TR) assay was compared with the Markit-M PA (MM) assay in the diagnosis of the prostate cancer. In patients with a serum prostate specific antigen (PSA) level higher than the cut-off values measured by either the TR assay or the MM assay (4.1 ng/ml and 3.7 ng/ml, respectively), or a suspicious digital rectal examination, sextant biopsy of the prostate was performed. Among 227 patients undergoing biopsy, 64 patients were diagnosed as having prostate cancer. There was a significant difference of serum PSA values between patients with and without prostate cancer in either assay. There was no significant difference between the assays with respect to diagnosing according to prostate cancer using receiver operating characteristic analysis. The correlation between TR and MM in 150 men with a serum Tandem-R PSA below 10 ng/ml was Y = 1.12X + 3.745 (R = 0.68, p < 0.001). The correlation coefficient for the relationship between TR and MM was only 0.68, indicating a poor correlation. Four of the 15 patients with MM values below 4.0 ng/ml calculated by transformation from MM to TR values had prostate cancer. This suggested that conversion of MM values to TR values in the low PSA range presents problems.