Free-to-total prostate specific antigen ratio in clinical staging of prostate cancer

Abstract

対象は前立腺肥大症56例, 前立腺限局癌36例, 局所進行癌が20例, 転移癌22例.治療前保存血清のfree PSA(F)とtotal PSA(T)をchemiluminescent enzyme immunoassayにて測定.骨転移はSolowayの分類に基づきEODに分類.臨床病期との相関にはSpearmanの順位相関を用い検定.F/T比は前立腺癌では非癌よりも有意に低値を示した.非転移癌56例と転移癌22例では有意差を認めず.臨床病期との相関はtPSAはfPSAやF/T比よりも優れていた.骨転移限局群と広範群でF/T比に有意差は認めなかった

The value of the free-to-total serum prostate-specific antigen (f/t PSA) ratio was compared with that of the total prostate specific antigen (tPSA) value for the prediction of clinical stage in patients with prostate cancer. The f/t PSA ratio was obtained from the frozen sera of 56 untreated patients with histologically proven BPH and 78 patients with prostate cancer. The clinical stage was organ-confined in 36, locally advanced in 20 and metastatic in 22 patients. Serum levels of free PSA (fPSA) and tPSA were determined using a chemiluminescent enzyme immunoassay. The f/t PSA ratio was calculated by dividing the fPSA value by the tPSA value and was compared with tPSA and fPSA in the correlation with clinical stage via the Spearman rank correlation test. Patients with prostate cancer had a significantly lower f/t PSA ratio than patients with BPH. The f/t PSA ratio did not differ between patients with clinically localized and metastatic cancer. tPSA and fPSA reflected the clinical stage and the extent of bone metastasis more accurately than the f/t PSA ratio. The extent of bone metastasis had no effect on the PSA ratio. The f/t PSA ratio had no additional value in clinical staging compared to tPSA. Our study suggests that the f/t PSA ratio does not reflect tumor load.