Expression change of serum total prostate specific antigen with age and its significance in differential diagnosis of prostate cancer

Abstract

Objective To evaluate the changes of serum total prostate specific antigen (TPSA) with age and its significance in differential diagnosis of prostate cancer (PCa) and prostatic hyperplasia (BPH). Methods TPSA and free prostate specific antigen (FPSA) in 146 cases of PCa, 108 cases of BPH and 210 cases of healthy subjects were detected by electrochemiluminescence. Results There was a positive correlation between age and serum TPSA level (r = 0.265, P < 0.01). The levels of TPSA in PCa and BPH groups were (85.40±56.70) μg/L and (7.90±7.00) μg/L, and the difference was statistically significant (t = 8.310, P = 0.001); FPSA levels were (5.16±4.90) μg/L, (1.50±1.36) μg/L, and the difference was statistically significant (t = 3.152, P = 0.030). In patients with TPSA levels ranging from 4.0 to 20.0 μg/L (diagnostic gray zone), the levels of TPSA in PCa and BPH groups were (8.82±4.01) μg/L and (8.41±3.95) μg/L, and the difference had no statistical significance (t = 0.198, P = 0.256); The levels of FPSA were (1.18±0.91) μg/L and (2.32±1.20) μg/L, the ratio of FPSA/TPSA were 0.12±0.08 and 0.24±0.23, and the differences were statistically significant (t = 23.56, P = 0.020; t = 32.45, P = 0.006). When FPSA/TPSA ratio was 0.16, its sensitivity and specificity for PCa were 84.4 % and 79.8 %, respectively. Conclusions Serum TPSA levels vary with age, and 95 % of all age groups should be used as the medical criterion to improve the specificity and accuracy of PSA in diagnosing with PCa. The ratio of FPSA/TPSA has a significant clinical value in differential diagnosis of PCa and BPH in patients with TPSA in diagnostic gray zone. Key words: Prostate specific antigen; Reference value; Diagnostic grey zone; Diagnosis, differential