Serum TPS, PSA, and PAP values in relapsing stage D2 adenocarcinoma of the prostate

Abstract

Serum tissue polypeptide-specific antigen (TPS), prostate-specific antigen (PSA), and prostatic acid phosphatase (PAP) concentrations were serially measured in 31 prostate cancer patients with bone metastases who had relapsed following hormonal therapy. Of these subjects 7 had well-differentiated cancer (G1), 13 patients were assessed to have moderately differentiated tumor (G2) while in 11 subjects poorly differentiated tumor (C13) was found. With increasing tumor grade (G1 to G3), a proportional increase in mean TPS value was found while the increase in respective PAP serotest values was not linear. Simultaneously measured mean PSA values showed a curved effect. Both PSA and PAP serotest concentrations depend on the respective hormone-dependent gene expressions that gradually decrease with tumor dedifferentiation. Therefore, in progressive hormonally treated stage D2 prostate cancer patients an androgen-independent TPS serotest seems to be a useful clinical addition for monitoring protocols. The combined use of TPS, PSA, and PAP seems to give a better reflection of tumor status. According to the bone scan data metastatic tumor mass in G3 carcinomas was virtually equal to cancer burden in G2 tumors. Hence, the marked elevation of TPS serotest values in G3 adenocarcinomas could not be attributed to greater tumor mass but was most likely due to an increase in proliferation rate. Some authors have recently proposed cytokeratins 8, 18, and 19 to be the origin of TPS serum findings. However, cytokeratin content has been proven to be lower in G3 tumors than in better-differentiated neoplasms. TPS serotest values in progressive G3 cancer patients strikingly higher than the TPS levels in G1 and G2 tumors, when correlated with the above data, seem to imply TPS is a cell proliferation marker rather than an indicator of tumor degradation.