前立腺生検前のPSA再測定の意義

Abstract

1988年8月～2002年2月に初回前立腺生検を行った患者のうち、生検の適応と決めてから3ヵ月以内に生検を実施した症例で、生検目的の入院時に再度の前立腺特異抗原(PSA)測定がなされていた344例中の288例について、2回のPSA測定値の比較、f/t比の比較を行った。288例中前立腺癌は93例であり、陰性例は195例で、2回のPSA測定間隔は1～90日(平均31.4日)で、全例で検討すると"decision"と"just before"は各平均13.0ng/mlと11.7ng/mlで"just berore"は有意に低値であった。癌、陰性例に分けて各"decision"と"just before"を比較すると、陰性例では有意に"just before"が低い傾向はあるが有意差はなく、癌陰性例を症状有無で分け検討すると、有症状症例で"decision"と"just before"は各平均11.2ng/mlと9.2ng/mlでPSA値低下が顕著であった。

To examine the natural change of prostate-specific antigen (PSA), we compared two PSA values, the first value with which we decided to perform prostate biopsy and the value obtained by remeasurement just before biopsy. To exclude cases with extremely high PSA, we examined 288 cases in which PSA was less than 50 ng/ml for comparison. Of the 288 cases, 93 were diagnosed with prostate cancer (CaP). The interval between the two PSA measurements was 1-90 days (average of 31.4 days). The first and second values were an average of 13.0 and 11.7 ng/ml, respectively, and the second value was significantly lower than the first value. When we divided them into CaP cases and non-CaPthe two cases, a significant difference between PSA values was found only in the non-CaP cases. Moreover, in the non-CaP cases with some clinical symptoms, the difference in PSA was marked between the first and second values, which averaged 11.2 and 9.2 ng/ml, respectively. When we decide to perform a biopsy, we should recognize that PSA sometimes is lower on re-measurement. Particularly in symptomatic cases, it is worth re-measuring PSA, which may save unnecessary biopsies.