T1a,T1b前立腺癌検出におけるPSA, PSAD値の有用性について

Abstract

前立腺肥大症の診断で手術を施行し, 組織診断で良性であった179症例と癌が検出された23症例の特性をretrospectiveに検討した. 1)前立腺肥大症症例において前立腺体積とPSA値は有意に相関した. 2)Tla癌の特性は前立腺肥大症と差はなく, 鑑別はできなかった. 3)Tlb癌のPSA値, PSAD値は前立腺肥大症に比べ有意に高く, 前立腺体積, 切除重量は有意に小さかった. 4)Tla, Tlb癌の鑑別におけるPSAのcut-off値としては8ng/mlが, PSADのcut-off値としては0.25ng/ml/mlが適当であった.またこの時見落とされる癌の多くは鑑別困難なTla癌で, 予測される癌の多くはTlb癌であった. 5)PSADを用いることでPSAより特異性が改善された

The clinical significance of preoperative prostate specific antigen (PSA) and PSA density (PSAD) in distinguishing stage T1a and T1b prostate cancer from benign prostatic hyperplasia (BPH) was studied retrospectively in men who had undergone surgery for BPH. A total of 202 clinically BPH patients underwent transurethral resection of prostate (TURP) or retropubic prostatectomy, and histopathological findings were BPH in 179 patients, T1a cancer in 10 patients and T1b cancer in 13 patients. The T1a cancer group was similar to the BPH group in all parameters. The PSA and PSAD values in the T1b cancer group were significantly higher than those in the BPH group (P < 0.001). Prostate volume and amount of tissue resected in the T1b cancer group were significantly smaller than those in the BPH group (p < 0.001). The cut-off values of PSA and PSAD were examined with T1a and T1b cancer as a positive control and histologically proven BPH as a negative control. When 8.0 ng/ml was used as the PSA cut-off value, the sensitivity was 65% and specificity was 70%. When 0.25 ng/ml/ml was used as the PSAD cut-off value, the sensitivity and specificity were 65% and 75%, respectively. PSAD was useful for improving the specificity. Almost all the cases undetected by using both cut-off values were of T1a cancer. The receiver operating characteristics curve demonstrated that at any point, PSAD was a better detector for distinguishing T1a, T1b cancer from BPH, focusing especially in the range of PSA level between 6.0 and 10.0 ng/ml. These findings suggest that PSA and PSAD are useful parameters in distinguishing T1b cancer from BPH before surgery.