COMPARISON OF PROSTATE SECRETORY PROTEIN WITH PROSTATE-SPECIFIC ANTIGEN AND PROSTATIC ACID-PHOSPHATASE AS A SERUM BIOMARKER FOR DIAGNOSIS AND MONITORING PATIENTS WITH PROSTATE CARCINOMA

Serum prostate secretory protein (PSP) levels were measured in 49 pati ents with benign prostatic hyperplasia (BPH), 144 patients with variou s stages of prostatic carcinoma (Cap), and 82 CaP patients who were fo llowed serially. PSP values were compared with serum levels of prostat e specific antigen (PSA) and prostatic acid phosphatase (PAP). In the BPH group, PSP was elevated (> 10 ng/ml) in 41% of patients, whereas P SA (> 4 ng/ml) and PAP (> 3.3 ng/ml) were elevated in 39% and 23% of t he cases, respectively. PSP levels were elevated in 48% of the CaP pre treatment specimens, compared to 79% for PSA and 40% for PAP. PSP leve ls in cancer patients who had intracapsular disease were about two to three times higher than those observed for PAP. PSP was found to be th e only marker elevated in eight (6%) pretreatment CaP patient serum sp ecimens, while PAP was never found to be elevated when PSA was normal. PSP serum concentrations correlated with the clinical course of the d isease in 79% of patients, compared with 90% for PSA and 66% for PAP. In certain patients, monitored over time, disease correlation was refl ected in serum values with only a single biomarker, i.e., 1% with PAP, 8% with PSP, and 10% with PSA. This study has shown that PSP is a les s sensitive serum biomarker than PSA, but more sensitive than PAP for detection and monitoring the early stages of prostate cancer. This sug gests that PSP as a biomarker may be a useful adjunct for the manageme nt of a subpopulation of low-stage and -grade CaP. (C) 1993 Wiley-Liss , Inc.