[Discrepancy between the serum levels of gamma seminoprotein and prostate-specific antigen in patients with prostatic neoplasms. Both true or either untrue].

Serum levels of prostatic acid phosphatase (PAP), gamma-seminoprotein (gamma-Sm) and prostate-specific antigen (PSA) were determined simultaneously in 57 patients with benign prostatic hyperplasia (BPH) and in 50 untreated patients with prostatic cancer (adenocarcinoma, N = 47 and non-adenocarcinoma, N = 3). The correlations between the serum levels of gamma-Sm and PSA in these patients were assessed by linear regression analysis. Some fundamental studies were added for explaining the causes of discrepancy between the serum levels of gamma-Sm and PSA. All of BPH group underwent transurethral resection of the prostate (TURP) and the sera were obtained for measurements before, immediately after and 18 hours after TURP. The gamma-Sm correlated well with the PSA in the sera obtained before (r = 0.76) and 18 hours after (r = 0.73) TURP. However, there was no correlation (r = 0.26) between them in the sera obtained immediately after TURP. In 47 untreated patients with adenocarcinoma of the prostate, no significant correlation (r = 0.19) between serum levels of gamma-Sm and PSA was observed, although there was correlation (r = 0.51) between those of PAP and PSA. When these patients were classified into two groups, M0 (stage A-C; N = 26) and M1 (stage D; N = 21), however, the serum gamma-Sm correlated with the serum PSA in M0 group (r = 0.57), but didn't in M1 group (r = 0.11). Furthermore, the differences in the means of PAP (p less than 0.05) and PSA (p less than 0.001) between M0 group and M1 group were statistically significant, although the serum gamma-Sm failed to distinguish M0 from M1. The anti-PSA antibody of "PSA Kit" reacted against the standard gamma-Sm adopted from "gamma-Sm Kit". Surprisingly, the anti-gamma-Sm antibody of "gamma-Sm Kit" also reacted against the standard PSA adopted from "PSA Kit". The gamma-Sm and PSA apparently cross-reacted each other. The quantitative analyses with serial dilution of the sera were done by using each assay in 3 patients whose serum levels of gamma-Sm were markedly different from those of PSA. The dilution curve for PAP appeared to be rectilineal, and that for PSA also appeared to be approximately rectilineal. However, the gamma-Sm assay failed to be proportional. In conclusion, the correlation between serum levels of gamma-Sm and PSA was absent in certain circumstances, when the true values of them were expected to be much higher than those determined.(ABSTRACT TRUNCATED AT 400 WORDS)