OBJECTIVESTo investigate the applicable value of complexed prostate-specific antigen (PSA) in the diagnosis of prostate cancer.

METHODSFrom July 2001 to May 2002, 152 consecutive patients (21 were prostate cancer and 131 were benign prostate hyperplasia proved by pathologic diagnosis) whose serum total PSA (TPSA) ranged from 0.2 microgram/L to 21.9 micrograms/L were accessed. The measurement of total PSA, free PSA (FPSA) and complexed PSA was performed by chemiluminescence immuno-assay method. The correlation of TPSA and CPSA was analysed by SPPS 10.0. The receiver operating characteristic curves were generated by plotting the sensitivity versus specificity.

RESULTSArea under the curve was calculated for each assay. Logistic regression analysis was used to evaluate the ability of CPSA, TPSA and FPSA/TPSA. Area under the ROC curve of CPSA, TPSA and FPSA/TPSA ratio were 0.811, 0.799 and 0.376, respectively. The specificity for the complexed PSA, TPSA and FPSA/FPSA ratio were 62%, 57% and 4.7%, respectively, at cutoffs yielding 95% sensitivity. CPSA was determined to be the best index among the three ones by logistic regression analysis.

CONCLUSIONSThe CPSA and TPSA level in serum may provide good differentiation effect of prostate cancer and benign prostate hyperplasia than FPSA/TPSA ratio. The CPSA performs better than TPSA. At the same sensitivity, CPSA has higher specificity.