Intraindividual variation in total and percent free prostate-specific antigen levels in prostate cancer suspects

A monolithic single-chip point-of-care platform for metabolomic prostate cancer detection

There is a global unmet need for rapid and cost-effective prognostic and diagnostic tools that can be used at the bedside or in the doctor's office to reduce the impact of serious disease. Many cancers are diagnosed late, leading to costly treatment and reduced life expectancy. With prostate cancer, the absence of a reliable test has inhibited the adoption of screening programs. We report a microelectronic point-of-care metabolite biomarker measurement platform and use it for prostate cancer detection. The platform, using an array of photodetectors configured to operate with targeted, multiplexed, colorimetric assays confined in monolithically integrated passive microfluidic channels, completes a combined assay of 4 metabolites in a drop of human plasma in under 2 min. A preliminary clinical study using l-amino acids, glutamate, choline, and sarcosine was used to train a cross-validated random forest algorithm. The system demonstrated sensitivity to prostate cancer of 94% with a specificity of 70% and an area under the curve of 0.78. The technology can implement many similar assay panels and hence has the potential to revolutionize low-cost, rapid, point-of-care testing.

Psychological impact of serial prostate-specific antigen tests in Japanese men waiting for prostate biopsy

BACKGROUND

It is common to repeat prostate-specific antigen (PSA) measurements for men with intermediate PSA elevation before prostate biopsy. In this scenario, men with persistently elevated PSA values may have considerable psychological distress. We attempted to determine whether elevated PSA values have psychological effects on these men in association with the timing of measurement, PSA kinetics, and biopsy results.

METHODS

In order to investigate the initial and late effects of PSA tests on psychological distress during serial measurements, two groups of men with screen-positive results (PSA ≥3 ng/ml) were studied-205 men whose first questionnaires regarding anxiety and depression were taken at initial screening (group A), and 103 men whose questionnaires were taken at repeated measurement for prior PSA elevation (group B).

RESULTS

The level of distress was generally low. There were no significant differences in distress between the two groups, suggesting a constant psychological effect by elevated PSA values over a long period of time. The distress of men in group A increased significantly as PSA levels rose and decreased when they fell to normal range. On the other hand, the distress of men in group B did not change regardless of PSA kinetics, indicating that their psychological condition seemed susceptible to subtle PSA change only in the initial phase of measurements. Unexpectedly, men with benign results showed insignificant but higher distress after prostate biopsy.

CONCLUSIONS

Although a small fraction of men have psychological distress caused by changes in PSA levels, the benefits, risks (psychological and physical), and limitations of PSA tests must be adequately explained to the patients before entering the screening program.

Serial Percent Free Prostate Specific Antigen in Combination with Prostate Specific Antigen for Population Based Early Detection of Prostate Cancer

PURPOSE

We characterized the diagnostic properties of serial percent free prostate specific antigen in relation to prostate specific antigen in a multiethnic, multiracial cohort of healthy men.

MATERIALS AND METHODS

A total of 6,982 percent free prostate specific antigen and prostate specific antigen measurements were obtained from participants in a greater than 12-year Texas screening study comprising 1,625 men who never underwent biopsy, 497 who underwent 1 or more biopsies negative for prostate cancer and 61 diagnosed with prostate cancer. We evaluated the ROC AUC of percent free prostate specific antigen and the proportion of patients with fluctuating values across multiple visits determined according to 2 thresholds (less than 15% vs 25%). The proportion of cancer cases in which percent free prostate specific antigen indicated a positive test before prostate specific antigen greater than 4 ng/ml did and the number of negative biopsies that would have been spared by negative percent free prostate specific antigen test results were calculated.

RESULTS

Percent free prostate specific antigen fluctuated around its threshold of less than 25% (less than 15%) in 38.3% (78.1%), 42.2% (20.9%), and 11.4% (25.7%) of patients never biopsied, and with negative and positive biopsies, respectively. At the same thresholds, percent free prostate specific antigen tested positive earlier than prostate specific antigen in 71.4% and 34.2% of cancer cases, respectively. Among men with multiple negative biopsies and PSA greater than 4 ng/ml, percent free PSA would have tested negative in 31.6% and 65.8%, respectively.

CONCLUSIONS

Percent free prostate specific antigen should accompany prostate specific antigen testing to potentially spare unnecessary biopsies or detect cancer earlier. When near the threshold, both tests should be repeated due to commonly observed fluctuation.

Prostate-specific antigen testing across the spectrum of prostate cancer

Prostate-specific antigen (PSA) is a protein produced by the prostate, and this protein may be elevated for several reasons, including prostatitis, benign prostatic hypertrophy and/or cancer. PSA is not cancer-specific, cannot be used as a cancer marker and it has been demonstrated that there is no level of PSA that is definitive for prostate cancer. The value of the PSA test varies when used for screening, diagnosis, prognosis or as a signal of disease recurrence. Misuse of the test for screening has created unnecessary anxiety and costs, and has led to the significant overdiagnosis and overtreatment of men. More important than whether or not to screen is how one acts upon the data from a single test; with the exception of extremely high double- or triple-digit levels of PSA, it is prudent only to use a single PSA determination as a baseline, with biopsy and cancer treatment reserved for those with significant PSA changes over time, or for those with clinical manifestations mandating immediate therapy. Using the PSA test to monitor disease progression or recurrence is appropriate, provided one understands that absolute levels of PSA are rarely meaningful; it is the relative change in PSA levels over time that provides insight, but not definitive proof of a cancerous condition necessitating therapy. PSA secretion is under hormonal control and thus PSA levels may be affected differently by the type of drug therapy, by the stage of a patients' disease, and by genetic factors suggesting some men are 'high PSA producers'. Until a validated alternative test for prostate cancer is found and adopted, the current flawed PSA test needs to be used more judiciously and not used for routine screening as studies have demonstrated that screening, as defined, does not lead to a reduction in patient mortality. All men, their families and their physicians need to understand the significant limitations of PSA testing.

Intra-individual short-term variability of prostate-specific antigen and other kallikrein markers in a serial collection of blood from men under evaluation for prostate cancer

STUDY TYPE

Diagnostic (exploratory cohort).

LEVEL OF EVIDENCE

2b.

OBJECTIVE

To assess variation of total prostate-specific antigen (tPSA), free PSA (fPSA), percent fPSA, human glandular kallikrein 2 (hK2) and intact PSA measured three times within 2 weeks. Knowledge of the variation in an individual's PSA level is important for clinical decision-making.

PATIENTS AND METHODS

Study participants were 149 patients referred for prostate biopsy, of which 97 had benign disease and 52 had prostate cancer. Three blood samples were drawn with a median of 4 h between first and second samples and 12 days between first and third samples. Variability was described by absolute differences, ratios and intra-individual coefficients of variation. Total PSA, fPSA, hK2 and intact PSA were measured in anticoagulated blood plasma.

RESULTS

At baseline, the median tPSA was 6.8 (interquartile range, 4.5-9.6) ng/mL. The intra-individual variation was low for all biomarkers, and lowest for tPSA. For 80% of participants, the ratio between first and second time points for tPSA was in the range 0.91-1.09 and the ratio for percent fPSA was in the range 0.89-1.15. Total coefficients of variation between time 1 and 2 for tPSA, fPSA, percent fPSA, hK2 and intact PSA were 4.0%, 6.6%, 6.0%, 9.2% and 9.5%, respectively. The measurements taken several days apart varied more than those taken on the same day, although the variation between both time points was not large.

CONCLUSIONS

The intra-individual variation for all the kallikrein-like markers studied was relatively small, especially for samples drawn the same day. Few cases are reclassified between the time points. This indicates the high short-term biological and technical reproducibility of the tests in clinical use.

Incidental diagnosis of a PSA-negative prostate cancer by 18FDG PET/CT in a patient with hypopharyngeal cancer

Diagnosis of prostate cancer (PC) still remains critical as non-invasive screening with prostate specific-antigen (PSA) lacks to indicate malignancy of the prostate in some cases. Recent research has shown that clinically meaningful PC can develop in patients with a PSA value <4 ng/ml, frequently defined as upper limit of normal serum PSA levels. Furthermore, both morphological (computed tomography (CT), magnetic resonance imaging, transrectal ultrasound) and functional imaging with (18)fluorodeoxyglucose positron emission tomography (FDG-PET) are associated with several limitations for primary diagnosis of PC. We report a case of an incidentally diagnosed PSA-negative PC by (18)FDG PET/CT in a patient with a previous diagnosis of a hypopharyngeal cancer.