Effect of prostatic biopsy on free-to-total prostate-specific antigen ratio in patients with prostate cancer

Serum core-type fucosylated prostate-specific antigen index for the detection of high-risk prostate cancer

It is known that core-type fucosylation is higher in prostate cancer cells than in other cancer cell types and is associated with high-risk prostate cancer. Here, we developed an automated microcapillary electrophoresis-based immunoassay system for measuring serum core-type fucosylated prostate-specific antigen (PSA) and evaluated whether the serum fucosylated PSA index (FPI) can detect high-risk prostate cancer. Core-type fucosylated-free PSA was measured by our automated microcapillary electrophoresis-based immunoassay system with Pholiota squarrosa lectin. The FPI was calculated from total PSA and the percentage of fucosylated-free PSA. The optimum model to predict Gleason grade (GG) ≥2 was constructed by multivariate logistic regression analysis. Discrimination was assessed by determining the area under the receiver operator characteristic curve (AUC). The study included 252 men who underwent prostate needle biopsy due to elevated serum PSA levels (4-20 ng/mL), including 138 with GG ≥2. A higher FPI was significantly associated with GG (P < .0001). Multivariate logistic regression analysis showed that age, prostate volume and FPI were significant predictors of GG ≥2. The AUC of FPI and the model were 0.729 (95% confidence interval [CI]: 0.668-0.790) and 0.837 (95% CI: 0.788-0.886), respectively, compared to 0.629 (95% CI: 0.561-0.698) for PSA. Decision curve analysis showed the superior benefit of FPI and the model when compared to PSA. In a cohort with serum PSA levels <20 ng/mL, FPI could differentiate high-risk prostate cancer from biopsy-negative or low-risk prostate cancer. Therefore, FPI could be a useful adjunct in prostate biopsy counseling for men with abnormal PSA levels.

Advantages of prostate-specific antigen (PSA) clearance model over simple PSA half-life computation to describe PSA decrease after prostate adenomectomy

OBJECTIVES

A population kinetic approach based on PSA clearance (CL(PSA)) may be a more rational strategy to characterize prostate-specific antigen (PSA) decrease profile after prostate surgery than the commonly used method (half-life from mono/bi-exponential models).

METHODS

We used 182 post-adenomectomy PSA concentrations from 56 benign prostatic hyperplasia patients to build, with NONMEM software, a multi-exponential and a CL(PSA) model for comparison.

RESULTS

The best multi-exponential model was PSA(t)=4.96e(-)(0.269t)+3.10e(-)(0.16t)+0.746e(+)(0.0002t) with a stable median residual PSA at 0.64 ng/mL. The best model parametrized with clearance was CL(PSA)=0.0229()(AGE/69)(3.78). Akaike information criteria and standard errors favored the CL(PSA) model. Median peripheral zone and transitional zone productions were 0.034 ng/mL/cm(3) and 0.136 ng/mL/g. A threshold at 2 ng/mL on day 90 allowed for a diagnostic of biochemical relapse diagnostic.

CONCLUSIONS

The population CL(PSA) model was superior to the multi-exponential approach for investigating individual post-adenomectomy PSA decreases.

Evolution of free, complexed, and total serum prostate-specific antigen and their ratios during 1 year of follow-up of men with febrile urinary tract infection

OBJECTIVES

To determine the serum values of free, complexed, and total prostate-specific antigen (PSA) and their ratios in men with febrile urinary tract infection (UTI) during 1 year of follow-up.

METHODS

A total of 54 men were prospectively enrolled in the study, and serum samples were obtained at the acute stage of the UTI and after 1, 3, 6, and 12 months.

RESULTS

Most men had a rise (median 3.1, 7.2, and 14.1 ng/mL, respectively) in free PSA (fPSA), complexed PSA (cPSA), and total PSA (tPSA) during the acute phase of the UTI. After 1 month, fPSA rapidly decreased to levels that were maintained during the rest of the follow-up period, and cPSA and tPSA declined more slowly. At 1, 3, and 6 months after the infection the fPSA/tPSA and fPSA/cPSA ratios were abnormal in one half to two thirds of the men (median ratio 11%, 15%, and 16% and 17%, 24%, and 24%, respectively), comparable to findings in patients with prostate cancer.

CONCLUSIONS

These results confirmed that the prostate is involved in men with febrile UTI. The low fPSA/tPSA and fPSA/cPSA ratios in combination with sustained elevations of cPSA and tPSA for up to 6 months after UTI could be falsely interpreted as a sign of prostate cancer. The prolonged elevation of cPSA indicates a long-lasting inflammation of the nonadenomatous parts of the prostate.