Complexed PSA performance for prostate cancer detection in an African-American population

Comparison of the clinical value of complexed PSA and total PSA in the discrimination between benign prostatic hyperplasia and prostate cancer

BACKGROUND

To compare the clinical value of the measurement of complex and total PSA in the discrimination between benign prostatic hyperplasia (BPH) and prostate cancer.

METHODS

In serum samples collected from 166 men with histopathologically proven clinically localized prostate cancer and of 97 men with BPH, total prostate-specific antigen (PSA), complexed PSA and the free to total PSA ratio were determined. The statistical analysis was done by the comparison of the receiver operator characteristic (ROC) curves.

RESULTS

The areas under the ROC curves were 0.776 for total PSA, 0.799 for complexed PSA (total PSA vs. cPSA: p < 0.0001) and 0.812 for the free to total PSA ratio. With a cut-off of 3.0 ng/ml for complexed PSA, the sensitivity was 90%, the specificity 58%, the positive and the negative predictive values 79 and 78%, respectively. With a cut-off of 4.0 ng/ml for total PSA, the sensitivity was 87%, the specificity 59%, the positive and the negative predictive values were 78 and 72%, respectively.

CONCLUSIONS

There was a statistically significant advantage for complexed PSA compared to total PSA in the discrimination between BPH and prostate cancer. The difference was, however, small and its clinical relevance is questionable.

Complexed PSA improves prostate cancer detection: Results from a multicenter Japanese clinical trial

OBJECTIVES

To compare the distribution of total and complexed prostate-specific antigen (cPSA) in men with and without prostate cancer with another studied population and to ascertain whether cPSA could enhance the detection of prostate cancer in Japanese men.

METHODS

A total of 760 men whose serum total PSA (tPSA) values ranged from 1.0 to 100 ng/mL were enrolled. Serum samples for tPSA and cPSA (ADVIA Centaur) were obtained in all cases. The area under the curve was calculated for comparison of the tPSA and cPSA values. We calculated the number of cancers missed and false-positive results at various cutoff values of cPSA compared with the conventional tPSA threshold of 4.0 ng/mL.

RESULTS

Prostate cancer was detected in 268 (35.3%) of 760 patients. cPSA was greater than 8.3 ng/mL (equivalent to 10.0 ng/mL tPSA) in 46.6% of the men with cancer. The area under the curve for cPSA (0.741) was significantly better than that for tPSA (0.721, P <0.001). At a sensitivity of 85% to 95%, significant differences were found in the corresponding specificity between tPSA and cPSA. cPSA at a 3.0-ng/mL threshold detected an identical number of cancers as a tPSA cutoff of 4.0 ng/mL; however, it decreased the false-positive results by 28 cases.

CONCLUSIONS

To our knowledge, this is the first report of the distribution of cPSA in Japanese men using a urologic referral population. cPSA can be an alternative to tPSA as the first screening test. A substantial number of men in Japan with prostate cancer are currently diagnosed with a tPSA value greater than 10.0 ng/mL.

Observed effect of age and body mass index on total and complexed PSA: analysis from a national screening program

OBJECTIVES

To assess the effect of aging and body mass index (BMI) on both serum total prostate-specific antigen (tPSA) and complexed PSA (cPSA) from the results of the 2003 Prostate Cancer Awareness Week national screening database.

METHODS

A total of 12,943 men were screened for prostate cancer. Of these, 4458 men had simultaneous measurements of tPSA and cPSA. Height and weight were used to calculate the BMI. The subjects were grouped by decade of age and categorized as either obese or nonobese with a cutoff BMI of 30 kg/m2. The rates of increase in mean tPSA and cPSA between consecutive decades were compared. The relationship among BMI, PSA, and cPSA was also analyzed using multivariate regression analysis.

RESULTS

The median age of those screened was 60 years. The median PSA and cPSA was 1.10 and 0.69 ng/dL, respectively. Both serum tPSA and cPSA levels showed an exponential increase with advancing age. The ratio of cPSA/tPSA remained relatively constant at 0.6. Compared with the nonobese cohort, men with a BMI of 30 kg/m2 or more had significantly lower tPSA and cPSA levels across all age groups (P <0.01). The overall odds ratio for all age groups was 1.8 (95% confidence interval 1.2 to 2.3).

CONCLUSIONS

Both tPSA and cPSA levels increased with age. Across age groups, men with a greater BMI had significantly lower cPSA and tPSA levels. The clinical significance of age-adjusted cutoff levels for PSA in obese men for the diagnosis of prostate cancer should be explored further in future prospective clinical trials.