Clinical evaluation of γ‐seminoprotein in prostate cancer

Abstract

Gamma‐seminoprotein (γ‐Sm), a potential new marker for prostate cancer, has been evaluated with a sandwich‐type enzyme immunoassay (EIA). This assay system has been confirmed to have a sensitivity and detectable range of 3.0 and 3.0–100 ng/ml, respectively, with a high reproducibility (≈ 6% coefficient of variation between assays). A total of 256 serum samples were drawn from normal Japanese subjects for detection of γ‐Sm. Serum γ‐Sm was undetectable (< 3.0 ng/ml) in 26 samples from 26 females. In 230 male cases, serum γ‐Sm levels ranged from less than 3.0 to 4.0 ng/ml. These values were not related to age. An upper normal limit of 3.6 ng/ml was calculated for 99 percentile Japanese males (n = 103) over 50 years of age. Serum γ‐Sm was detected in 192 untreated male patients with urological diseases. Gamma Sm levels (mean ± SD) in each disease were as follows: prostate cancer (n = 64) 11.0 ± 17.9 ng/ml; benign prostatic hypertrophy (n = 50), 3.02 ± 0.113; bladder cancer (n = 58), 3.13 ± 0.514; and renal adenocarcinoma (n = 30), 3.26 ± 1.01. Serum γ‐Sm levels were statistically higher (p < 0.05) in the prostate cancer group, however, there was no statistical difference in γ‐Sm levels among clinical stages or histopathologic grades. Furthermore, serum γ‐Sm values showed no correlation (r = 0.3870) with prostatic acid phosphatase (PAP), but were slightly correlated to prostate antigen (PA) levels (r = 0.6980) in patients with prostate cancer. These results suggest that γ‐Sm is a potential tumor marker of prostate cancer and that serially detected serum γ‐Sm levels could be used to monitor the disease.