Biological variation of prostate specific antigen levels in serum: an evaluation of day-to-day physiological fluctuations in a well-defined cohort of 24 patients

Finger-actuated microfluidic chip integrated with visual immunoassay for ultrasensitive detection of PSA in whole blood

Cumbersome preprocessing and specialized manual operations in clinical blood samples remain a significant challenge for achieving high sensitivity and accurate quantification in point-of-care testing. In this paper, a finger-driven integrated microfluidic chip based on visualization of single nanoparticle scattering was proposed for the detection of prostate-specific antigen (PSA) in the whole blood. To control on-chip fluid, a finger-driven module based on a Tesla valve was designed to unidirectionally regulate fluid mixing and separation in the microchannel. In addition, a membrane separation unit was designed to efficiently separate blood cells and serum, reducing interference from blood cells in the detection process. For quantitative PSA concentration detection, a Multi-functional core-satellite magnetic probe was constructed by using the principle of complementary base pairing of ligands on the surface of gold nanoparticles and magnetic beads. In the presence of target PSA, the constructed core-satellite nanostructure was decomposed, producing a characteristic fluorescence signal and releasing gold nanoparticles with green scattering spots under dark-field microscopy. By correlating the concentration with the number of green scattering spots, cancer risk levels were displayed intuitively using a traffic light system. This biosensor achieves an ultra-low detection limit of 0.5 pg/mL for PSA. Due to the ultra-sensitive ability in detection, the monitoring of PSA concentrations for patients during treatment was also demonstrated. Compared with other methods, this proposed microfluidic assay technology has the advantages of small sample volume, minimal operation, high sensitivity and accuracy. Overall, this biosensor provides a new approach for cancer recurrence monitoring and early diagnosis.

A new promising indicator in prostate cancer screening: Prostate-specific antigen fluctuation rate

OBJECTIVES

To evaluate whether PSA fluctuation can be used to predict the risk of prostate cancer.

MATERIALS AND METHODS

The study included 1244 patients who underwent prostate biopsy at Kartal Dr. Lutfi Kirdar City Hospital between 2013 and 2021 (848 in non-cancer; 396 in cancer). The patient's age, last two PSA values (PSA1 and PSA2) within three months before the biopsy, the duration between two PSAs (days), prostate size (g) and PSA density (PSAD) were all recorded. PSA fluctuation rate (PSAfr) was defined as the change rate between two PSA values.

RESULTS

PSAfr was significantly higher in the non-cancer group than in the prostate cancer group (15.2% (20.5) and 9.6% (14.4), P=.019). A Simple linear regression was used to examine the relationship between PSAfr and other factors such as age, PSA, PSAD, and prostate volume, but it was shown that these had no effect on PSA fluctuations. ROC analysis revealed a relatively low Area Under the Curve (AUC) for PSAfr (AUC, 0.584 (0.515-0.653)). However, the cut-off value of 12.35% was found to be significant, with a sensitivity of 58% and a specificity of 59% (P:.019, 95%CI). The odds ratio, adjusted for age, PSAD, and PSA2, was calculated as 0.545 (0.33-0.89) using logistic regression analysis to show the relationship between prostate cancer and PSAfr. As a result, those with high PSAfr were found to be 1.83 times less likely to be diagnosed with prostate cancer than those with low fluctuations.

CONCLUSION

PSAfr could be used in nomograms to predict prostate cancer risk and reduce the number of unnecessary biopsies.

Reframing How Physical Activity Reduces The Incidence of Clinically-Diagnosed Cancers: Appraising Exercise-Induced Immuno-Modulation As An Integral Mechanism

Undertaking a high volume of physical activity is associated with reduced risk of a broad range of clinically diagnosed cancers. These findings, which imply that physical activity induces physiological changes that avert or suppress neoplastic activity, are supported by preclinical intervention studies in rodents demonstrating that structured regular exercise commonly represses tumour growth. In Part 1 of this review, we summarise epidemiology and preclinical evidence linking physical activity or regular structured exercise with reduced cancer risk or tumour growth. Despite abundant evidence that physical activity commonly exerts anti-cancer effects, the mechanism(s)-of-action responsible for these beneficial outcomes is undefined and remains subject to ongoing speculation. In Part 2, we outline why altered immune regulation from physical activity - specifically to T cells - is likely an integral mechanism. We do this by first explaining how physical activity appears to modulate the cancer immunoediting process. In doing so, we highlight that augmented elimination of immunogenic cancer cells predominantly leads to the containment of cancers in a 'precancerous' or 'covert' equilibrium state, thus reducing the incidence of clinically diagnosed cancers among physically active individuals. In seeking to understand how physical activity might augment T cell function to avert cancer outgrowth, in Part 3 we appraise how physical activity affects the determinants of a successful T cell response against immunogenic cancer cells. Using the cancer immunogram as a basis for this evaluation, we assess the effects of physical activity on: (i) general T cell status in blood, (ii) T cell infiltration to tissues, (iii) presence of immune checkpoints associated with T cell exhaustion and anergy, (iv) presence of inflammatory inhibitors of T cells and (v) presence of metabolic inhibitors of T cells. The extent to which physical activity alters these determinants to reduce the risk of clinically diagnosed cancers - and whether physical activity changes these determinants in an interconnected or unrelated manner - is unresolved. Accordingly, we analyse how physical activity might alter each determinant, and we show how these changes may interconnect to explain how physical activity alters T cell regulation to prevent cancer outgrowth.

Critical review and meta-analysis of biological variation estimates for tumor markers

OBJECTIVES

Biological variation data (BV) can be used for different applications, but this depends on the availability of robust and relevant BV data. In this study, we aimed to summarize and appraise BV studies for tumor markers, to examine the influence of study population characteristics and concentrations on BV estimates and to discuss the applicability of BV data for tumor markers in clinical practice.

METHODS

Studies reporting BV data for tumor markers related to gastrointestinal, prostate, breast, ovarian, haematological, lung, and dermatological cancers were identified by a systematic literature search. Relevant studies were evaluated by the Biological Variation Data Critical Appraisal Checklist (BIVAC) and meta-analyses were performed for BIVAC compliant studies to deliver global estimates of within-subject (CV_I) and between-subject (CV_G) BV with 95% CI.

RESULTS

The systematic review identified 49 studies delivering results for 22 tumor markers; four papers received BIVAC grade A, 3 B, 27 C and 15 D. Out of these, 29 CV_I and 29 CV_G estimates met the criteria to be included in the meta-analysis. Robust data are lacking to conclude on the relationship between BV and different disease states and tumor marker concentrations.

CONCLUSIONS

This review identifies a lack of high-quality BV studies for many tumor markers and a need for delivery of BIVAC compliant studies, including in different, disease states and tumor marker concentrations. As of yet, the state-of-the-art may still be the most appropriate model to establish analytical performance specifications for the majority of tumor markers.

Personalised biopsy schedules based on risk of Gleason upgrading for patients with low-risk prostate cancer on active surveillance

OBJECTIVE

To develop a model and methodology for predicting the risk of Gleason upgrading in patients with prostate cancer on active surveillance (AS) and using the predicted risks to create risk-based personalised biopsy schedules as an alternative to one-size-fits-all schedules (e.g. annually). Furthermore, to assist patients and doctors in making shared decisions on biopsy schedules, by providing them quantitative estimates of the burden and benefit of opting for personalised vs any other schedule in AS. Lastly, to externally validate our model and implement it along with personalised schedules in a ready to use web-application.

PATIENTS AND METHODS

Repeat prostate-specific antigen (PSA) measurements, timing and results of previous biopsies, and age at baseline from the world's largest AS study, Prostate Cancer Research International Active Surveillance (PRIAS; 7813 patients, 1134 experienced upgrading). We fitted a Bayesian joint model for time-to-event and longitudinal data to this dataset. We then validated our model externally in the largest six AS cohorts of the Movember Foundation's third Global Action Plan (GAP3) database (>20 000 patients, 27 centres worldwide). Using the model predicted upgrading risks; we scheduled biopsies whenever a patient's upgrading risk was above a certain threshold. To assist patients/doctors in the choice of this threshold, and to compare the resulting personalised schedule with currently practiced schedules, along with the timing and the total number of biopsies (burden) planned, for each schedule we provided them with the time delay expected in detecting upgrading (shorter is better).

RESULTS

The cause-specific cumulative upgrading risk at the 5-year follow-up was 35% in PRIAS, and at most 50% in the GAP3 cohorts. In the PRIAS-based model, PSA velocity was a stronger predictor of upgrading (hazard ratio [HR] 2.47, 95% confidence interval [CI] 1.93-2.99) than the PSA level (HR 0.99, 95% CI 0.89-1.11). Our model had a moderate area under the receiver operating characteristic curve (0.6-0.7) in the validation cohorts. The prediction error was moderate (0.1-0.2) in theGAP3 cohorts where the impact of the PSA level and velocity on upgrading risk was similar to PRIAS, but large (0.2-0.3) otherwise. Our model required re-calibration of baseline upgrading risk in the validation cohorts. We implemented the validated models and the methodology for personalised schedules in a web-application (http://tiny.cc/biopsy).

CONCLUSIONS

We successfully developed and validated a model for predicting upgrading risk, and providing risk-based personalised biopsy decisions in AS of prostate cancer. Personalised prostate biopsies are a novel alternative to fixed one-size-fits-all schedules, which may help to reduce unnecessary prostate biopsies, while maintaining cancer control. The model and schedules made available via a web-application enable shared decision-making on biopsy schedules by comparing fixed and personalised schedules on total biopsies and expected time delay in detecting upgrading.

Does extent of prostate-specific antigen fluctuation can predict Gleason score upgrading in low-risk prostate cancer patients?

OBJECTIVE

To evaluate the effect of prostate-specific antigen (PSA) fluctuation on Gleason score (GS) upgrading, disease upstaging, oncological outcomes in low-risk prostate cancer (PCa) patients who underwent robot-assisted laparoscopic radical prostatectomy (RARP) and met the inclusion criteria for active surveillance (AS).

MATERIAL AND METHODS

Data of 354 low-risk PCa patients who underwent RARP were retrospectively evaluated. Patients were divided into two groups: PSA fluctuation rate<9.5%/month (Group 1, n=192) and >9.5%/month (Group 2, n=162). Mainly compared parameters were GS upgrading, disease upstaging, biochemical recurrence (BCR) and surgical margin positivity (SMP) rates.

RESULTS

GS upgrading, disease upstaging and SMP were detected in 128 (36.2%), 56 (15.8%) and 42 (11.9%) patients, respectively. After a median follow-up of 46 months, BCR was observed in 40 (11.3%) patients. GS upgrading (41.1% vs. 30.2%, p=0.033), disease upstaging (19.8% vs. 11.1%, p=0.028), SMP (15.1% vs. 8%, p=0.035) and BCR development (15.6% vs. 6.2%, p=0.005) rates were statistically significantly higher in Group 1 than Group 2. In multivariate analysis, digital rectal examination positivity, the presence of two positive cores and low PSA fluctuation rate were found to be significant predictors of GS upgrading.

CONCLUSION

Low PSA fluctuation rate is associated with higher GS upgrading.

Beyond the PSA test: How to better stratify a patient's risk of prostate cancer

The primary method of screening for and detecting prostate cancer is the prostate-specific antigen (PSA) test. Although this test is very prostate-specific, it is not cancer-specific; conditions other than prostate cancer can cause an elevated PSA. Many efforts have been made to discover more specific tests and methods beyond the PSA. This article describes several literature-supported tests and methods to better stratify a man's risk of having prostate cancer.

Biomarkers for evaluation of prostate cancer prognosis

Prostate cancer, with a lifetime prevalence of one in six men, is the second cause of malignancy-related death and the most prevalent cancer in men in many countries. Nowadays, prostate cancer diagnosis is often based on the use of biomarkers, especially prostate-specific antigen (PSA) which can result in enhanced detection at earlier stage and decreasing in the number of metastatic patients. However, because of the low specificity of PSA, unnecessary biopsies and mistaken diagnoses frequently occur. Prostate cancer has various features so prognosis following diagnosis is greatly variable. There is a requirement for new prognostic biomarkers, particularly to differentiate between inactive and aggressive forms of disease, to improve clinical management of prostate cancer. Research continues into finding additional markers that may allow this goal to be attained. We here selected a group of candidate biomarkers including PSA, PSA velocity, percentage free PSA, TGFβ1, AMACR, chromogranin A, IL-6, IGFBPs, PSCA, biomarkers related to cell cycle regulation, apoptosis, PTEN, androgen receptor, cellular adhesion and angiogenesis, and also prognostic biomarkers with Genomic tests for discussion. This provides an outline of biomarkers that are presently of prognostic interest in prostate cancer investigation.

Prostate-Specific Antigen fluctuation: what does it mean in diagnosis of prostate cancer?

OBJECTIVE

To investigate whether prostate-specific antigen (PSA) fluctuation correlates with a prostate cancer and to assess whether PSA fluctuation could be used for diagnosis of prostate cancer.

MATERIALS AND METHODS

Our study included 229 patients who were performed a prostate biopsy (non-cancer group, 177; prostate cancer group, 52). Enrolled patients were provided twice PSA tests within 6 months. PSA fluctuation (%/month) was defined as a change rate of PSA per a month. Independent t test was used to compare between two groups. Receiver operator characteristic curve was used to assess the availability as a differential diagnostic tool and the correlation. Simple linear regression was performed to analyze a correlation between PSA fluctuation and other factors such as age, PSA, PSA density, and prostate volume.

RESULTS

There were significant differences in PSA, PSA density, percentage of free PSA, and PSA fluctuation between two groups. PSA fluctuation was significantly greater in non-cancer group than prostate cancer group (19.95 ± 23.34%/month vs 9.63 ± 8.57%/ month, P=0.004). The most optimal cut-off value of PSA fluctuation was defined as 8.48%/month (sensitivity, 61.6%; specificity, 59.6%; AUC, 0.633; P=0.004). In a simple linear regression model, only PSA level was significantly correlated with PSA fluctuation.

CONCLUSION

Patients with wide PSA fluctuations, although baseline PSA levels are high, might have a low risk of diagnosis with prostate cancer. Thus, serial PSA measurements could be an option in patients with an elevated PSA level.

The complexity of PSA interpretation in clinical practice

Prostate specific antigen (PSA) is central to the diagnosis of prostate cancer. Laboratories quote cut-off reference ranges for PSA but values within these boundaries do not equate with an absence of cancer nor do levels above the range equate with its presence. Convention places the cut-off value at 4 μg/L when calibrated to the Hybritech immunoassay technology and 3.0 or 3.1 μg/L if the PSA methods are calibrated to the WHO IRP 96/670 standard. The prevalence of prostate cancer in screened normal men over 55 years of age with PSA values less than 4 μg/L (Hybritech method) is 10.1% at a PSA of 0.6-1.0 μg/L. About 12.5% of these will be high grade. Two major randomised trials reported on PSA screening. The European trial (ERSPC) reported a risk reduction for prostate cancer death of 21% in the screened group but the US PLCO trial found no benefit. PSA results depend on calibration and there is a 22% difference between the older Hybritech and newer WHO standardisation. Biological variation in PSA is a geometric mean of 7.3%. External quality assessment schemes show wide variation in the performance of PSA analysis. Neither the American College of Physicians nor the UK National Health Service recommends screening except when there is increased risk through family history or ethnicity. Laboratories should detail their method calibration in each report and clinicians should be alerted to the potential misclassification of patients through PSA variation.

Prostate cancer detection rate in patients with fluctuating prostate-specific antigen levels on the repeat prostate biopsy

Purpose:

To evaluate whether the risk of prostate cancer was different according to the pattern of fluctuation in prostate-specific antigen (PSA) levels in patients undergoing repeat transrectal ultrasound-guided prostate biopsy (TRUS-Bx).

Methods:

From March 2003 to December 2012, 492 patients underwent repeat TRUS-Bx. The patients were stratified into 3 groups based on the PSA fluctuation pattern: group 1 (continuous elevation of PSA, n=169), group 2 (PSA fluctuation with PSA velocity [PSAV]≥1.0 ng/mL/yr, n=123), and group 3 (PSA fluctuation with PSAV<1.0 ng/mL/yr, n=200).

Results:

Prostate cancer was detected in 112 of 492 patients (22.8%) in the repeat biopsy set. According to the PSA fluctuation pattern, prostate cancer detection rates at repeat TRUS-Bx were 29.6% (50/169) for patients with continuously increasing PSA, 30.1% (37/123) for PSA fluctuation with PSAV ≥1.0 ng/mL/yr, and 12.5% (25/200) for PSA fluctuation with PSAV <1.0 ng/mL/yr. Multivariate analysis showed that PSA fluctuation pattern and high grade prostatic intraepithelial neoplasia at initial TRUS-Bx were the predictive parameters for positive repeat biopsies. Among the 96 patients (85.7%) who underwent radical prostatectomy, no significant differences in pathologic outcomes were found according to the PSA fluctuation pattern.

Conclusions:

The current study shows that the risk of prostate cancer at repeat TRUS-Bx was higher in men with a fluctuating PSA level and PSAV≥1.0 ng/mL/yr than in those with a fluctuating PSA level and PSAV<1.0 ng/mL/yr.

Hospitalization decreases serum prostate-specific antigen values compared with outpatient values in patients with benign prostatic diseases

Purpose

To investigate whether hospitalization influences serum prostate-specific antigen (PSA) values.

Materials and Methods

Transrectal ultrasound-guided prostate biopsies were performed for detecting prostate cancer in 2,017 patients between February 2001 and April 2011 at Ajou University Hospital. Of those patients, 416 patients who were hospitalized for prostate biopsies, whose serum PSA values were measured at the outpatient department within 1 month of admission and also just after admission, and who had negative prostate biopsy results were included in the present study. We retrospectively reviewed the data of the 416 patients and compared the serum PSA values measured in the outpatient department with those measured during hospitalization.

Results

Among all 416 patients, the interval between the two PSA measurements was 22.2 days (range, 3 to 30 days) and the prostate size measured by transrectal ultrasonography was 53.63 mL (range, 12.8 to 197.9 mL). Among all patients, mean serum PSA levels measured during hospitalization were significantly lower than those measured in the outpatient department (6.69 ng/mL vs. 8.01 ng/mL, p<0.001). When stratified according to age, the presence or absence of chronic prostatitis in the biopsy pathology, serum PSA levels, and prostate size, the serum PSA levels measured during hospitalization were significantly lower than those measured in the outpatient department in all subgroups, except in cases aged 20 to 39 years and those with PSA <4 ng/mL, in whom no significant differences were shown.

Conclusions

Hospitalization decreases serum PSA values compared with those measured on an outpatient basis in patients with benign prostatic diseases. Therefore, serum PSA values should be checked on an outpatient basis for serial monitoring.

The relationship between prostate volume and prostate-specific antigen variability: data from the Baltimore Longitudinal Study of Aging and the Johns Hopkins Active Surveillance Program

Study Type--Prognostic (cohort). Level of Evidence 2b. What's known on the subject? And what does the study add? Previous studies have attempted to characterize the normal biological variability in PSA among men without prostate cancer. These reports suggest that PSA variability is unrelated to age, but there are conflicting data on its association with the baseline PSA level. There are limited published data regarding the effects of prostate volume on PSA variability. A prior study assessing whether prostate volume changes would confound the use of PSA velocity in clinical practice reported that prostate volume changes were not significantly related to PSA changes. This study did not directly address the effect of baseline prostate volume on serial PSA variability. The objective of the current study was to further examine the relationship between prostate volume and PSA variability. Our hypothesis was that larger baseline prostate volume would be associated with increased PSA variability in men without known prostate cancer and in those with suspected small-volume disease. The results of the study suggest that baseline PSA, not prostate volume, is the primary driver of PSA variability in these populations.

OBJECTIVE

• To clarify the relationship between serial prostate-specific antigen (PSA) variability and prostate volume in both cancer-free participants from the Baltimore Longitudinal Study of Aging (BLSA) and patients with low-risk prostate cancer from the Johns Hopkins Active Surveillance Program (AS).

MATERIALS AND METHODS

• In all, 287 men from the BLSA and 131 patients from the AS were included in the analysis, all with at least two PSA measurements and concurrent prostate volume measurements. • PSA variability was calculated in ng/mL per year, and a linear mixed-effects model was used to determine the relative effects of prostate volume, baseline PSA and age on PSA change over time.

RESULTS

• In a model with prostate volume, age and baseline PSA, there was no significant relationship between prostate volume and PSA variability (BLSA, P= 0.57; AS, P= 0.49). • Only baseline PSA showed a significant relationship to PSA yearly variability (PSAYV) (P < 0.001). Specifically, a one unit higher baseline PSA (ng/mL) corresponded on average to 0.09 and 0.06 ng/mL per year higher PSAYV in the BLSA and AS populations, respectively.

CONCLUSIONS

• The results of the present study suggest that the primary driver of PSA variability is the baseline PSA level, rather than prostate volume. • Clinicians might consider the baseline PSA level to help predict the expected variability in serial PSA measurements.

Predicting prostate biopsy result in men with prostate specific antigen 2.0 to 10.0 ng/ml using an investigational prostate cancer methylation assay

PURPOSE

The inadequacies of prostate specific antigen testing have created a need for novel markers for prostate cancer screening. The investigational ProCaM™ prostate cancer methylation assay detects aberrant methylation of DNA in cells associated with prostate cancer. We describe a large, prospective, multicenter study done to verify the performance of this assay.

MATERIALS AND METHODS

The assay is designed to detect epigenetic modifications in the 3 markers GSTP1, RARβ2 and APC, which are indicative of prostate cancer. A total of 232 men with cancer and 283 without cancer from 18 clinical sites were evaluated by trained operators at central testing laboratories. Study inclusion criteria were age 40 to 75 years, total prostate specific antigen between 2.0 and 10.0 ng/ml, and a digital rectal examination result. All participants signed an informed consent form and underwent transrectal ultrasound guided needle biopsy with 10 or more cores.

RESULTS

Assay sensitivity was 60%, specificity was 80% and the informative rate was 97%. Assay predictive accuracy was higher than that of age, digital rectal examination, family history, prostate specific antigen, prior negative biopsy and prostate volume (AUC 0.73 vs 0.52 to 0.66, p <0.038). Risk factors plus the assay improved overall predictive power (AUC 0.79, p = 0.001). A man with a positive prostate cancer methylation result was 7.7 times more likely to have high grade cancer.

CONCLUSIONS

The prostate cancer methylation assay correlated with positive biopsy and with Gleason score. This assay has the potential to add value to the biopsy decision making process by improving current prostate cancer screening algorithms to more accurately identify men with prostate cancer.

Antimicrobial therapy for asymptomatic patients with elevated prostate-specific antigen: can the change in prostate-specific antigen reliably guide prostate biopsy decisions?

OBJECTIVES

To assess the effects of a 4-week levofloxacin course on PSA in asymptomatic men with elevated prostate-specific antigen (PSA) and on prostate biopsy decision.

METHODS

Fifty asymptomatic men with elevated PSA (4.0-10.0 ng/dl) were given levofloxacin 500 mg/day for 4 weeks followed by repeat PSA. Prostate biopsy was recommended at the end of the study. We compared pre- and post-treatment PSA as well as PSA changes between prostate cancer cases and non-cancer patients.

RESULTS

Mean (±SD) PSA decreased from 6.91 ± 2.13 to 6.05 ± 3.0 ng/dl after antimicrobial treatment (p = 0.025). Twenty-five (56.8%) patients had a post-treatment decrease in PSA, including 20 (45.5%) patients to <4.0 ng/dl and/or >25% of the initial PSA value. The difference in PSA change between prostate cancer and non-cancer patients was not statistically significant (p = 0.104).

CONCLUSIONS

Levofloxacin resulted in an overall decrease in PSA for asymptomatic men with PSA in the 4-10 ng/dl range. PSA changes, however, were not significantly different between patients with prostate cancer and non-cancer patients. Prostate cancer was detected in 20% of patients with a clinically relevant PSA decline.

Tumor markers in prostate cancer I: blood-based markers

The introduction of total prostate specific antigen (total PSA) testing in blood has revolutionized the detection and management of men with prostate cancer (PCa). The objective of this review was to discuss the challenges of PCa biomarker research, definition of the type of PCa biomarkers, the statistical considerations for biomarker discovery and validation, and to review the literature regarding total PSA velocity and novel blood-based biomarkers.

METHODS

An English-language literature review of the Medline database (1990 to August 2010) of published data on blood-based biomarkers and PCa was undertaken.

RESULTS

The inherent biological variability of total PSA levels affects the interpretation of any single result. Men who will eventually develop PCa have increased total PSA levels years or decades before the cancer is diagnosed. Total PSA velocity improves predictiveness of total PSA only marginally, limiting its value for PCa screening and prognostication. The combination of PSA molecular forms and other biomarkers improve PCa detection substantially. Several novel blood-based biomarkers such as human glandular kallikrein 2 (hK2), urokinase plasminogen activator (uPA) and its receptor (uPAR), transforming growth factor-beta 1 (TGF-β1); interleukin-6 (IL-6) and its receptor (IL-6R) may help PCa diagnosis, staging, prognostication, and monitoring. Panels of biomarkers that capture the biologic potential of PCa are in the process of being validated for PCa prognostication.

CONCLUSIONS

PSA is a strong prognostic marker for long-term risk of clinically relevant cancer. However, there is a need for novel biomarkers that aid clinical decision making about biopsy and initial treatment. There is no doubt that progress will continue based on the integrated collaboration of researchers, clinicians and biomedical firms.

Yearly prostate specific antigen and digital rectal examination fluctuations in a screened population

PURPOSE

Prostate biopsy is often recommended based on increases in prostate specific antigen and/or abnormal digital rectal examination. We investigated the stability of a single positive test during the next 3 consecutive years.

MATERIALS AND METHODS

A total of 2,578 participants in a San Antonio screening cohort with 2 or more consecutive annual prostate specific antigen and digital rectal examination tests were identified. Occurrences of an increased prostate specific antigen (2.5 ng/ml or greater) followed by 1 or more nonincreased prostate specific antigen results were compared with similar fluctuations of digital rectal examination from abnormal to normal.

RESULTS

In 2,272 men who did not have a biopsy during the study, in 23.3% of 744 incidences of an increased prostate specific antigen with 1 year of followup, the next prostate specific antigen was not increased. In 19.5% of 462 incidences of an increased prostate specific antigen with 2 years of followup, the next 2 consecutive prostate specific antigen levels were not increased. Finally, in 17.5% of 285 incidences of an increased prostate specific antigen with 3 years of followup, the next 3 consecutive prostate specific antigens were not increased. Rates were similar but lower in 221 men with 1 or more negative biopsies during the study and in 85 men in whom prostate cancer eventually developed during the study. In contrast, approximately 70% of abnormal digital rectal examinations were normal the following year even in patients with prostate cancer, and in the majority of incidences remained normal the next 2 to 3 consecutive years.

CONCLUSIONS

Occurrences of reversed prostate specific antigen cut point or abnormal digital rectal examination based decisions to biopsy 1 or more years after the initial test are not uncommon, suggesting repetition of these tests.

New onset of heterophilic antibody interference in prostate-specific antigen measurement occurring during the period of post-prostatectomy prostate-specific antigen monitoring

Laboratories evaluated whether an interference was causing a false-positive PSA for the Immulite 2000 immunoassay after a time course of increasing prostate-specific antigen (PSA) in a post-prostatectomy patient led to salvage therapy, which had no effect on the elevated PSA. Serial dilutions of PSA for the patient sample (6.1 ng/mL; post-prostatectomy reference range: <0.1 ng/mL [undetectable]) were linear ( r > 0.99). However, the PSA measurement was reduced to 0.1 ng/mL after pretreatment of the sample with heterophilic antibody blocking reagent. PSA was undetectable (<0.1 ng/mL) when measured using two alternative immunoassays. These results were consistent with the presence of heterophilic antibody interference for the Immulite 2000 assay. In this case, heterophilic antibody interference with PSA measurement must have originated during the period of post-prostatectomy monitoring, and the apparent progressive increases in PSA may have been due solely to the progressive increase of this heterophilic antibody assay interference. In the absence of clinical correlation, positive PSA monitoring results should always be assessed for heterophilic antibody interference for at least one time point.

Obesity and prostate cancer mortality

It has long been known that obesity modestly increases the risk of prostate cancer mortality. Only recently, however, have studies examined whether this association is due to an increased risk of aggressive disease and/or worse outcomes following initial diagnosis and treatment. This distinction is important, because if obesity increases the risk of metastasis and death following treatment, weight loss could be an effective adjunct treatment. We now have good evidence that obesity increases the risk of aggressive prostate cancer, but reduces the risk of low-grade, nonaggressive cancer. In addition, several studies have found that obesity increases the risk of biochemical recurrence following prostatectomy; however, the few studies that have examined more definitive end points, metastases and death, have been less consistent. Furthermore, there are no studies that have examined whether weight loss after diagnosis favorably affects prostate cancer outcome. While accepting the current limitations in our knowledge base, it is our opinion that it is appropriate for physicians to counsel their patients to lose weight following prostate cancer diagnosis and motivate this change in behavior by emphasising the likely benefit of improving long-term outcome.

[Prognostic significance of "sawtooth" PSA and "stepwise" PSA]

OBJECTIVE

To evaluate the risk of diagnosing prostate cancer on repeated biopsies in patients with fluctuating PSA values compared to patients with stable or regularly increasing PSA values.

MATERIAL

Retrospective study conducted on the 2000-2003 databases of 2 French teaching hospitals. Selected patients had a first negative prostatic biopsy, then at least one other series of prostatic biopsies. "Sawtooth" PSA was defined by a PSA value less than that of the previous assay. Other cases were described as "stepwise" PSA.

RESULTS

191 patients were included: 79 in the "sawtooth" group and 112 in the "stepwise" group. Prostate cancer was diagnosed in 53 patients (27.7%), on the second prostatic biopsy 39 cases. Prostate cancer was detected in 17 (21.5%) of the 79 patients of the "sawtooth" group. This proportion was not significantly different (p = 0.14) from that observed in patients of the "stepwise" group: 36/112 (32.1%). No significant difference in terms of age, stage, Gleason score and initial PSA was observed between patients with a diagnosis of prostate cancer in the "sawtooth" and "stepwise" groups.

CONCLUSION

In our study, the risk of diagnosing prostate cancer on repeated prostatic biopsies was not greater in patients with "stepwise" PSA compared to patients with "sawtooth" PSA.

Assessment of Prostate-Specific Antigen Doubling Time in Prediction of Prostate Cancer on Needle Biopsy

OBJECTIVES

Prostate-specific antigen (PSA) kinetics have failed to predict for the presence of prostate cancer in screening populations in which many patients harbor subclinical disease. We hypothesized that the prebiopsy PSA doubling time (PSADT) and PSA velocity (PSAV) could predict for cancer detection in a referral population with a suspicion of prostate cancer.

METHODS

Data were collected from 1699 consecutive veterans with a PSA level of 10 ng/mL or less who underwent prostate biopsy. Logistic regression analysis was performed on the following: age, race, family history, digital rectal examination findings, PSA, PSA density, PSADT, PSAV, prostate volume, and ultrasound lesions. Model building was accomplished with 70% of the data, and validation was done using the remaining 30%. These data were also analyzed using classification and regression tree analysis.

RESULTS

Using logistic regression analysis (P <0.05) on the model building set, prostate cancer was associated with age (older than 70 years), PSA level (greater than 2.9 ng/mL), PSA density (more than 0.12 ng/mL/cm3), digital rectal examination findings, and the presence of a lesion on ultrasonography. A PSADT of 2 to 5 years was marginally associated with prostate cancer detection (odds ratio 1.6, 95% confidence interval 1.1 to 2.3), and a PSADT of less than 2 years or longer than 5 years and PSAV were not predictive. On classification and regression tree analysis, PSADT was not selected as a predictive factor. Furthermore, neither PSADT nor PSAV was predictive of Gleason score 7 or worse cancer.

CONCLUSIONS

In contrast to its prognostic value after the diagnosis of prostate cancer has been established, PSA kinetics offer little to clinical decision making as predictors of cancer or high-grade cancer in men with a PSA level of 10 ng/mL or less.

Obesity is negatively associated with prostate-specific antigen in U.S. men, 2001-2004

BACKGROUND

Recent studies have shown a negative association between body mass index (BMI) and prostate-specific antigen (PSA), a commonly used serum marker for the detection and diagnosis of prostate cancer. We have examined the association between several anthropometric measures and PSA in a nationally representative sample of men.

METHODS

We analyzed data from the 2001-2004 National Health and Nutrition Examination Survey. Participants in this study were men ages >or=40 years without previously diagnosed prostate cancer who had PSA measured. Height, weight, waist circumference, BMI, triceps skinfold, subscapular skinfold, and calculated total body water were examined categorically by quintiles using multiple linear regression models. All tests of significance were two sided.

RESULTS

Among white men, we report a trend for decreasing PSA with increasing weight, BMI, waist circumference, triceps skinfold thickness, and calculated total body water. Among Mexican American men, we found a trend for decreasing PSA with increasing BMI, and among black men we found a trend for decreasing PSA with increasing triceps thickness. None of the interaction terms between race/ethnicity and any of the anthropometric measures were statistically significant. Controlling for age and race/ethnicity in the multiple linear regression model, we found moderate declines in PSA with a 1 SD increase in BMI [5.9% decrease (95% confidence interval, -9.0% to -2.8%) in geometric mean PSA per 5.2-unit increase], weight [5.9% decline (-8.8% to -2.8%) per 17.7-kg increase], waist circumference [6.6% decline (-9.4% to -3.6%) per 13.4-cm increase], triceps skinfold [5.4% decline (-8.9% to -1.8%) per 6.4-mm increase], and calculated total body water [5.7% decline (-8.9% to -2.4%) per 6.5-liter increase].

CONCLUSION

Our population-based, nationally representative results expand the validity of previous studies on obesity and PSA. Higher weight, BMI, waist circumference, triceps skinfold, and total body water are associated with moderately lower PSA values. A prospective study is needed to verify whether this association affects the accuracy of the PSA test in obese men.

Interval from prostate biopsy to radical prostatectomy: Effect on PSA, Gleason sum, and risk of recurrence

OBJECTIVES

To determine whether the change in prostate-specific antigen (PSA), change in Gleason sum, and/or interval between prostate biopsy and radical prostatectomy have an association with biochemical recurrence.

METHODS

The relationship between biochemical recurrence and the interval between biopsy and surgery, as well as the rate and amount of change in PSA and Gleason sum from biopsy to surgery, was evaluated in 151 patients with prostate cancer treated with radical prostatectomy.

RESULTS

A statistically significant increase was found in PSA level and Gleason sum between biopsy and surgery (P = 0.01 and P < 0.0001, respectively). No significant association was found between prebiopsy PSA level (P = 0.27) or biopsy Gleason sum (P = 0.07) with biochemical recurrence as independent variables or in a combined model (P = 0.12). An association was also not found between recurrence and preprostatectomy PSA level (P = 0.15) or the rate of PSA change (P = 0.28) as independent variables. However, a significant association was found with the prostatectomy Gleason sum (P = 0.001). In a combined model, a significant association was noted between the preprostatectomy PSA level and prostatectomy specimen Gleason sum and biochemical recurrence (P = 0.003). No increased risk of biochemical recurrence was noted with increasing time from biopsy to prostatectomy (odds ratio 1.00) or the rate (odds ratio 1.03) and degree (odds ratio 1.30) of serum PSA or Gleason sum (odds ratio 1.07).

CONCLUSIONS

The interval between biopsy and radical prostatectomy is not a predictor of biochemical failure. An association was noted between an increased risk of biochemical failure and the amount of serum PSA and Gleason sum increase between biopsy and surgery.

Surgical management of prostate cancer: Advances based on a rational approach to the data

The management of localised prostate cancer has undergone important changes in the past two decades, with major improvements in surgical technique, a greater emphasis on structured assessment of quality of life, and a greater attempt to tailor treatment to biological risk. Disease diagnosis is predicated on identification of demographic risk factors, serum levels of prostate-specific antigen and its derivatives, and extended biopsy techniques. Surgical removal of the prostate may be accomplished by open or minimally invasive techniques and in experienced hands results in good functional outcomes a high rate of cure for those with organ confined disease. Radical prostatectomy is also appropriate in selected patients with locally advanced disease and after failed radiation therapy.

Potential survival advantage with early androgen deprivation for biochemical failure after external beam radiotherapy: The importance of accurately defining biochemical disease status

PURPOSE

We analyzed our experience treating localized prostate cancer to determine the impact of androgen deprivation (AD) on clinical outcome if administered at the time of isolated biochemical failure (BF) vs. after clinical failure (clinical failure), and the associated impact of various BF definitions.

METHODS

A total of 1,201 patients with stage T1-T3N0M0 prostate cancer were treated with external beam radiotherapy (EBRT) to a median dose of 66.6 Gy. Early AD was defined as administration of AD after BF, without evidence of clinical failure. Delayed AD was defined as administration of AD after clinical failure. Multiple BF definitions were tested for capacity to predict subsequent clinical failure. For each BF definition, outcome was compared for BF patients receiving early AD vs. no or delayed AD.

RESULTS

Five-year clinical failure (from date of BF) was 60% for patients who experienced a prostate-specific antigen rise to >/=3 ng/mL above nadir. For these patients, early AD was associated with decreased 5-year local failure (4% vs. 33%), distant metastasis (13% vs. 44%), cause-specific death (9% vs. 24%), and death due to any cause (32% vs. 48%), despite poorer prognostic factors in patients receiving early AD. On multivariate analysis, early AD remained independently significant for each of these end points.

CONCLUSION

The efficacy of AD after BF varies depending on the BF definition. When an optimal BF definition is applied, early AD decreases distant metastasis and improves survival. Prostate-specific antigen elevation to >/=2 or >/=3 ng/mL above nadir seems optimal in establishing clinically significant BF and the timing of AD intervention.

Intra-individual variation of serum prostate specific antigen levels in men with benign prostate biopsies

OBJECTIVE

To determine the intra-individual (physiological) variation of prostate-specific antigen (PSA) measurements in men after a benign prostatic biopsy.

PATIENTS AND METHODS

Sixty-four men were prospectively assessed, all of whom had a benign prostatic biopsy within the preceding 13 months. The degree of intra-individual variability was established by calculating the coefficient of variation on four PSA levels obtained from each patient weekly over a month.

RESULTS

Six patients were subsequently diagnosed with prostate cancer and their data are presented separately. In the remaining 58 patients the median (range) individual mean PSA value was 6.3 (0.5-34.1) ng/mL. The median (range) coefficient of variation within the group was 9.5 (2.4-76.1)%. There was a clear linear relationship between mean PSA level and the standard deviation.

CONCLUSION

In 48 of the 63 patients analysed, the coefficient of variation for serum PSA values in the group as a whole was greater than the variation claimed for the assay technique. The significance of the linear relationship between PSA and the standard deviation is discussed, with particular reference to those men who had a benign prostate biopsy.

Using splines to detect changes in PSA doubling times

BACKGROUND

PSA doubling time (PSADT) can predict the likelihood of clinical progression in patients with biochemical relapse after surgery or radiation for prostate cancer. Changes in PSA doubling time in response to therapy may be of clinical or investigational significance. How does one estimate PSADT before and after the initiation of therapy and determine if any change is statistically significant or simply the result of random variation? These are the type of questions addressed.

METHODS

Our technique uses a best-fitting spline (i.e., a broken-line approximation) to a graph of log PSA on time to estimate PSADTs before and after treatment initiation. A linear regression program is used to produce the fit and to evaluate the statistical significance of any change in PSADT. This method differs from previous methods in that it uses all the data, exploits the continuity of PSA at the time of treatment initiation, and allows one to make statistical significance statements about specific individuals.

RESULTS

Our technique is illustrated with data from a pilot clinical trial using a nutritional supplement in 12 men with prostate cancer. A detailed analysis of the first patient shows how the data are handled, how two lines of computer code are sufficient to fit the spline model, and how the doubling times and statistical significance of a change are read from the computer output. In the study, 9 of 12 patients had a statistically significant increase in doubling time. Because the study is preliminary and used only to illustrate our method, no medical discussion of the study is included. The last section of the study, in part expository, is devoted to explaining the underlying principles for those who may want to know not only what to do, but why it works.

CONCLUSIONS

The method presented here for determining changes in PSADT is both simple and broadly applicable. It allows the evaluation of the size and statistical significance of an observed change or increase in PSADT in response to therapy for prostate cancer. It can be done using essentially any statistical software and widely accepted statistical methods.

Improving the utility of prostate specific antigen (PSA) in the diagnosis of prostate cancer: the use of PSA derivatives and novel markers

Prostate specific antigen (PSA) testing is now a routine part of the investigation of men with suspected prostate cancer. While a very useful test it still has its problems, in particular its lack of specificity means abnormal results are often caused by benign disease. This review describes the current problems with PSA testing in prostate cancer diagnosis and highlights potential ways in which these may be reduced.

Different PSA assays lead to detection of prostate cancers with identical histological features

OBJECTIVE

Because different PSA assays still show a wide inter-assay variation, we wondered what influence these discrepancies could have on the individual tumour characteristics of the cancers that each of these assays detect in a critical low PSA range. We analysed five different PSA assays in a biopsy simulation with PSA cut-offs of 3.0 and 4.0 ng/ml.

MATERIALS AND METHODS

Randomly taken samples of 360 men with prostate cancer and 96 with benign prostatic disease from a screened population with PSA range of 1.0-6.0 ng/ml (Tandem-E) were investigated. In all cases the diagnosis was confirmed by sextant biopsies. One hundred and thirty-seven men (38%) underwent radical prostatectomy. Variability amongst assays was illustrated in terms of missed cancers and unnecessary biopsies, and in terms of pathologic features of detected cancers at both PSA cut-offs.

RESULTS

Compared to Tandem-E, all assays, except Access, showed significant differences in PSA measurements. Furthermore, none of the assays discriminated significantly between benign and malignant prostatic disease (p>0.05). Tandem-E and Elecsys lead significantly more frequently to the detection of cancers at the cost of more unnecessary biopsies compared to the other assays. Yet, at both PSA cut-offs the proportion of cancers with a certain pathologic grade or stage that were detected by each assay were approximately the same.

CONCLUSIONS

Our study shows that the use of different PSA assays only have consequences for the number, and not for the tumour characteristics of the prostate cancers that are detected. Thus, different PSA assays detect prostate cancers with the same tumour features.

The impact of intraoperative manipulation of the prostate on total and free prostate-specific antigen

OBJECTIVES

It is well documented that mechanical manipulation of the prostate can elevate total PSA (t-PSA) levels in serum. However, less is known about its effects on free PSA (f-PSA) and the free-to-total PSA ratio (f/t-PSA). We therefore examined the impact of prostate manipulation on t-PSA and f-PSA during surgical procedures involving the prostate.

METHODS

Intraoperative blood samples for t-PSA and f-PSA measurement (Hybritech) were collected every 15 min during 14 radical retropubic prostatectomies (RRP) and 10 radical cystoprostatectomies (RCP).

RESULTS

Prostatic manipulation induced significant elevations in t-PSA and f-PSA during RRP and RCP. Postmanipulatory peaks were markedly higher for f-PSA than for t-PSA. The mean maximum f-PSA levels showed a 4.3- (RRP) and 7.9-fold (RCP) increase, followed by a rapid decline after prostate removal. t-PSA increased 1.2- (RRP) and 1.3-fold (RCP), and declined more slowly. Postmanipulatory f/t-PSA ratios also increased significantly, reaching mean elevations of +0.29 and +0.28 over preoperative ratios during RRP and RCP, respectively.

CONCLUSIONS

Prostate manipulation can induce transient increases in t-PSA, f-PSA and f/t-PSA in benign and malignant prostates. The extent of these alterations and their course over time must be taken into account when postmanipulatory changes in PSA forms are investigated. Timing of postmanipulatory venipunctures and the molar response ratio of t-PSA assays used (equimolar versus nonequimolar) seem to have substantial impact on the results of such studies.

Practical application of biochemical failure definitions: what to do and when to do it

PURPOSE

The posttreatment prostate-specific antigen (PSA) profile can often be difficult to interpret after external beam radiotherapy for prostate cancer. We performed an extensive analysis of post-radiotherapy PSA measurements to determine the clinical significance of biochemical failure (BF) and the correlation of BF with clinical failure (CF) and cause-specific death (CSD).

MATERIALS AND METHODS

Between 1987 and 1997, 727 patients with clinical stage T1-T3 N0 M0 prostate cancer were treated with definitive external beam radiotherapy at William Beaumont Hospital and had at least five post-radiotherapy PSA levels and did not receive hormonal therapy for post-radiotherapy PSA elevations only (before evidence of CF). All patients received external beam radiotherapy alone (no adjuvant hormonal therapy) to a median total prostate dose of 66.6 Gy. More than 20 BF definitions were tested for their correlation with CF (any local failure or distant metastasis) and CSD. All BF definitions were tested for sensitivity, specificity, accuracy, and positive and negative value of predicting subsequent CF and CSD. The median follow-up was 5.0 years.

RESULTS

Three consecutive PSA rises yielded a 73% sensitivity, 76% specificity, and 75% overall accuracy for predicting CF. The 10-year CF rate (from the completion of radiotherapy) for those 251 patients demonstrating three consecutive rises (BF) was 64% vs. 14% for those patients who did not have three rises (biochemically controlled). Defining BF as a post-nadir increase to >or=3 ng/ml above the nadir yielded the highest accuracy of 87%. In addition, this definition also seemed to provide the greatest separation in CF rates: 82% for BF vs. 5% for biochemically controlled at 10 years after radiotherapy. CF rates were also calculated from the date of BF (e.g., date of third rise). The CF rates at 6 months and 2 years after the third PSA rise were 9% and 27%, respectively. The CF rates at 6 months and 2 years after an increase to >or=3 ng/ml above the nadir were 23% and 54%, respectively. Once a patient was classified as a BF, regardless of the BF definition, the CF rate varied markedly, depending on the pretreatment characteristics. For each BF definition, younger age at diagnosis, higher pretreatment PSA, and higher Gleason score independently predicted for CF after BF on Cox multiple regression analysis. For instance, patients with a pretreatment PSA <4.0 ng/ml demonstrated an 11% CF rate at 2 years after the third PSA rise vs. 46% after three rises with a pretreatment PSA >or=20.0 ng/ml. Similarly, patients with Gleason 2-4 had a 2-year CF rate of only 3% after a nadir >or=1.0 ng/ml vs. 47% for Gleason 8-10 at 2 years after a nadir >or=1.0 ng/ml. Although the CF rate also coincided with pretreatment characteristics when using >or=3 ng/ml above the nadir, CF rates remained high even for low-risk patients (e.g., 2-year CF of 48% for PSA <10.0 ng/ml, 41% for Gleason 2-4). In addition, a shorter time interval from nadir to nadir + 1 ng/ml or from nadir to nadir + 3 ng/ml (corresponding to a steeper slope in the PSA profile) independently predicted for CF.

CONCLUSION

Once the post-radiotherapy PSA profile reaches >or=3 ng/ml above the nadir, there is a high risk of clinical failure within a relatively short time period, for which treatment intervention may be considered, regardless of pretreatment characteristics. After a nadir >or=1.0 ng/ml or three consecutive rises, some patients (especially with low-risk pretreatment characteristics) may be considered for further PSA observation before treatment intervention.

Prostate-specific antigen in prostate cancer: a case study in the development of a tumor marker to monitor recurrence and assess response

The serum marker known as prostate-specific antigen (PSA) has established itself as the most important tool for the early detection of prostate cancer. However, more recent data indicate that (post-treatment) PSA and PSA kinetics can be used to predict the outcome of a variety of therapeutic interventions including radical prostatectomy, radiation therapy, androgen deprivation, and treatment of hormone-refractory prostate cancer. PSA recurrence after radiation therapy is now accepted as a harbinger of developing metastatic disease. The American Society for Therapeutic Radiation Oncology (ASTRO) consensus definition is the most widely accepted definition of failure after radiation therapy. Rather than using a specific PSA cutoff, three consecutive PSA rises was felt to be a more reliable indicator of biochemical failure. The PSA nadir (the lowest PSA level achieved after therapeutic intervention) also appears to correlate with the likelihood of remaining disease-free. Similarly, a rapid doubling time is a significant predictor of developing distant metastases. The most appropriate definition for biochemical (PSA) failure following radical prostatectomy is usually considered to be a non-zero value. As is the case after radiotherapy, there appears to be a relationship between the rate of rise of the PSA and the risk of distant failure following radical prostatectomy. In patients with metastatic disease, multiple studies appear to indicate that a fall in PSA, however measured, appears to be predictive of improved outcome in prostate cancer patients treated with androgen deprivation. Multiple reports of trials in the treatment of hormone-refractory prostate cancer (HRPC) appear to substantiate the observation that patients who have a greater than 50% decline in PSA have an improved survival. Correlation of PSA declines with other markers of clinical benefit, including clinically significant "subjective" end points such as pain control, have strengthened the argument that a PSA decline can serve as an intermediate endpoint in clinical trials involving HRPC patients.

Perineural invasion and MIB-1 positivity in addition to Gleason score are significant preoperative predictors of progression after radical retropubic prostatectomy for prostate cancer

We assessed the use of clinical stage, serum prostate specific antigen, DNA ploidy, proliferation, and traditional histologic findings from the biopsy to predict prostate cancer progression after radical retropubic prostatectomy. Between 1995 and 1998, 454 consecutive patients with cancer on biopsy were treated by radical retropubic prostatectomy. Preoperative serum prostate specific antigen, clinical stage, Gleason score, percentage of cores and surface area positive for cancer, perineural invasion, and DNA ploidy and MIB-1 immunostain quantitation by image analysis were evaluated in a multivariate Cox proportional hazards regression model to predict cancer progression. Cancer progression was defined as a postoperative serum prostate specific antigen level of > or = 0.4 ng/mL, local recurrence, or systemic progression. Mean follow-up was 3.4 years (range 17 days to 5.8 years). Cancer progression was observed in 73 patients with a mean time to progression of 2.1 years (range 33 days to 5.1 years). Gleason score (p <0.001), MIB-1 cancer proliferation (p = 0.008), and perineural invasion (p = 0.008) were significantly associated with progression. Patients with cancer Gleason scores of 7 and >7 had a 2.5-fold and nearly 4-fold increased risk, respectively, of cancer progression compared with patients with cancer Gleason scores of < or = 6. Patients with perineural invasion at biopsy were twice as likely to progress compared with patients without perineural invasion. Each 1-unit increase in MIB-1 on the natural logarithmic scale increased the risk of cancer progression by 64%. Cancer progression models that include serum prostate specific antigen and clinical stage may require revision to incorporate perineural invasion and MIB-1 proliferative activity in addition to Gleason score.

The role of molecular forms of prostate-specific antigen (PSA or hK3) and of human glandular kallikrein 2 (hK2) in the diagnosis and monitoring of prostate cancer and in extra-prostatic disease

Prostate-specific antigen (PSA or hK3) is a glandular kallikrein with abundant expression in the prostate that is widely used to detect and monitor prostate cancer (PCa), although the serum level is frequently elevated also in benign and inflammatory prostatic diseases. PSA testing is useful for early detection of localized PCa and for the detection of disease recurrence after treatment. However, PSA has failed to accurately estimate cancer volume and preoperative staging. There is no PSA level in serum that definitively distinguishes men with benign conditions from those with prostate cancer, although PCa is rare in men with PSA levels in serum < 2.0 ng/ml. This prompted searches for enhancing parameters to combine with PSA testing, such as PSA density, PSA velocity, and age-specific reference ranges. Due to the protease structure, PSA occurs in different molecular forms in serum and their concentrations vary according to the type of prostatic disease. Human glandular kallikrein 2 (hK2) is very similar to PSA, but expressed at higher levels in prostate adenocarcinoma than in normal prostate epithelium. Blood testing for hK2 combined with different PSA forms improves discrimination of men with benign prostatic disease from those with prostate cancer. Many data have also been reported on the extra-prostatic expression of both PSA and hK2, and it is now believed that they may both have functions in tissues outside the prostate.

Intraindividual variation of prostate specific antigen measurement and implications for early detection of prostate carcinoma

BACKGROUND

Many researchers have described intraindividual prostate specific antigen (PSA) variation, but its implications for a prostate carcinoma screening program have not been well appreciated. In this study, the author explored misclassification problems associated with intraindividual PSA variation.

METHODS

The previous research work on intraindividual PSA variation was reviewed and summarized. Then, on the basis of the results from the previous work and a simple measurement error model, the author estimated misclassification probabilities for a single PSA measurement.

RESULTS

With a variance-based approach of meta-analysis, the author derived a summary coefficient of variation (13.1%) of the intraindividual PSA variation from the previous relevant studies. They found that there were substantial risks for misclassification, especially among those with PSA values near the recommended cutoff point (4.0 ng/mL). For an individual with a true PSA level at 3.9 ng/mL, the risk for misclassification as PSA higher than 4.0 ng/mL was approximately 42%; for an individual with a true PSA value at 3.0 ng/mL, the risk was less than 1%.

CONCLUSIONS

Intraindividual PSA variation should become a part of interpreting PSA test results, especially for men with a PSA value near the cutoff point. Both sensitivity and specificity of PSA test reported in the literature have been underestimated, and the risk of prostate carcinoma associated with PSA test results has been biased down to the null (no effect) because of the intraindividual PSA variation.

Soluble transferrin receptor (sTfR) concentration quantified using two sTfR kits: analytical and clinical performance characteristics

We compared the analytical and clinical performance characteristics of the Ramco and R&D Systems enzyme-linked immunosorbent assays (ELISAs) for quantifying serum levels of soluble transferrin receptor (sTfR). In addition, we determined both the number of samples required to determine the true individual mean sTfR concentration for a single individual and the critical difference (CD) between serial measurements that indicates a statistically significant change in sTfR concentration. sTfR concentration was determined in 127 serum samples selected retrospectively from males (n=32) and non-pregnant (n=40) and pregnant women (n=55). Intra- and inter-assay precision for both methods was good (CV values 5--10%) to excellent (CV values <5%) over a wide range of sTfR concentrations. Correlation between these methods was good (r=0.93); however, sTfR values by the R&D kit were approximately 2.9 times higher than values obtained using the Ramco kit on the same serum samples. Nevertheless, receiver-operator characteristic (ROC) curve analysis demonstrated that the diagnostic accuracy of both assays in discriminating between patients with iron-deficiency anemia (IDA) or anemia of chronic disease (ACD) was high (area-under-the-curve (AUC) values >0.95) and not significantly different (P=0.480). We determined that a minimum of 8 samples are required to determine an individual's true sTfR concentration, while a >40% difference between serial sTfR measurements would be required to indicate a statistically significant change in sTfR concentration. We concluded that both the Ramco and R&D Systems sTfR methods have similar analytical and clinical performance characteristics and were likely to be equally useful in discriminating between patients with biochemically defined IDA or ACD.

Diagnosis of localized prostate cancer: 10 years of progress

Advances in the diagnosis of early stage disease, and particularly the introduction of prostate-specific antigen (PSA) testing, have had a dramatic effect on the presentation and clinical management of prostate cancer during the past ten years. As a result, there have been significant epidemiological changes in countries where early diagnosis is recommended. The importance of PSA testing for the diagnosis of localized prostate cancer has become well established in clinical practice and this is reflected by improved outcomes from definitive treatment. The contribution of PSA-related parameters and molecular forms of PSA both to cancer detection and prediction of pathological stage continue to be explored. Concerns about the reliability of the standard sextant biopsy technique for cancer detection relate to the need for re-biopsy in a growing number of patients with negative biopsies and an increasing proportion of patients with low volume, multifocal disease. In men with cancer, additional prognostic information can be derived from biopsy findings, with important therapeutic implications. This relates also to the need for reliable markers indicating pathological stage and risk of progression. The opportunities for the prevention of prostate cancer have grown with improved understanding of its biology and the genetic basis of the early steps associated with malignant transformation. In the future, the need for therapeutic intervention is likely to be most influenced by successful prevention strategies.

[Analysis of biologic changes in PSA blood concentration and free PSA percentage in patients with normal rectal digital examination]

OBJECTIVE

To study intra-individual variations in serum PSA and percent free PSA in patients with normal digital rectal examination.

MATERIAL AND METHODS

Analysis of changes in serum PSA levels and percent free PSA in two blood measurements conducted in 107 non-consecutive patients prior to prostate biopsy, over a period of time ranging from 23 to 60 days. Both total and free PSA were measured with two dual monoclonal antibody assays, Tandem-E and Tandem-R, Hybritech. Diagnosis was benign hyperplasia in 63 patients and cancer in 44.

RESULTS

PSA variations ranged between -6.8 and +3.2 ng/ml in BPH patients, and between -2.8 and +9.0 when cancer was detected. The median coefficient of variation was 15.4 and 15.7, respectively. Variations in percent free PSA ranged between -30.7 and +40.9 in the BPH group and between -17.9 and +15.8 in the cancer group. The median coefficient of variation was 32.2 and 32.3%, respectively. Should prostate biopsy had been indicated when percent free PSA was equal to or lower than 25 in the 4 to 10 ng/ml PSA range, 15% patients would have exhibited discrepancies. Sensitivity would have ranged between 100 and 94.4%, with a reduction rate in negative biopsies between 16.6 and 19.4%.

CONCLUSIONS

Intra-individual variations in serum PSA levels and percent free PSA may condition the decision of whether to perform a prostate biopsy.

Prostate-specific antigen

Prostate-specific antigen (PSA) has revolutionized the diagnosis and management of men with prostate cancer. Significant advances have been made since the early development of immunoassays. While PSA is useful for staging and monitoring of established disease, it has shown the greatest utility in the realm of early detection realm. PSA is the most important tumor marker; its importance in evaluating men for the possibility of prostate cancer is irrefutable. Enhancing specificity is a pressing need. In this regard, the recognition of the molecular forms of free PSA and complex PSA have shown the most promise and undoubtedly will result in fewer false-positive PSA test results. The salient literature is reviewed and commentary made on the current status of PSA with particular emphasis on methods to enhance its specificity in early detection and applications.

Screening for prostate cancer

Screening for prostate cancer has shown great promise in its ability to detect prostate cancer at a curable stage; however, significant problems exist with respect to our knowledge of its impact on prostate cancer mortality. For the properly informed patient with at least a 10-year life expectancy, it would seem that early detection efforts utilizing digital rectal examination (DRE) and serum prostate-specific antigen (PSA) determination are beneficial. Considerable controversy abounds about early detection and screening and will continue until definitive proof of decreased prostate cancer mortality as a result of effective early detection and treatment regimens is demonstrated. Until then, all men with at least a 10-year life expectancy should be counseled as to the potential benefits and risks. The salient literature is reviewed and commentary made as to the benefits of screening methods that can be invoked as well as their limitations and potential liabilities.

Effect of finasteride and/or terazosin on serum PSA: results of VA Cooperative Study #359

BACKGROUND

Medical management of benign prostatic hyperplasia (BPH) giving rise to lower urinary tract symptomatology (LUTS) has emerged as the mainstay for first-line therapy. Prostate-specific antigen (PSA) is the most important method of detecting prostate carcinoma. The effect of finasteride on PSA has been widely reported. Little data exist with respect to alpha-adrenergic blocking therapy in men treated for BPH. In the present investigation we set out to evaluate the effect of these two forms of therapy.

METHODS

Patients enrolled in the VA Cooperative Study #359 trial were evaluated. This study evaluated men with moderate LUTS owing to BPH in four treatment groups: placebo (P), finasteride (F), terazosin (T), and combination of finasteride plus terazosin (C). Men were recruited at 31 VA medical centers and had a baseline in 52-week PSA determination at the respective sites.

RESULTS

There was no significant difference in baseline PSA between four groups (mean range, 2.0-2.9 ng/ml). Statistically significant reduction in PSA levels was observed at 52 weeks in the F and C arms (P < 0.001), whereas significant increases were observed in the T and P arms (P < 0.01). Additionally, there was no significant difference in PSA response between the T and P arms. Thirty percent of men in the C or F arms had more than 40-60% reduction of PSA. In contrast, the majority of men on T or P had less than 40% change in PSA. Only 35% of men on F or C had the expected 40-60% reduction in PSA level.

CONCLUSIONS

These data demonstrate no clinically significant effect of T on PSA level. The heterogeneity of PSA response to F may make monitoring patients for the development of prostate cancer problematic.

On the standardization of total prostate-specific antigen: an exercise with two reference preparations

In this study, 112 serum samples were analyzed for total prostate-specific antigen with three well-established assays i.e. Tandem R and Tandem E (both from Hybritech Inc., San Diego, USA) and Prostatus Free/Total from Wallac Oy, Turku, Finland. Thirty-two samples were collected from prostate cancer patients, 32 from patients with benign prostate hyperplasia and 48 from men participating in a screening study for prostate cancer. The aim of the study was to compare the results before and after recalculation with the data obtained with two reference preparations for total prostate-specific antigen: Stanford 90:10 PSA Calibrator and Certified Reference Material 613 Prostate-Specific Antigen. Comparing the actual results revealed almost perfect correlations between Tandem R and Tandem E and between both Tandem assays and Prostatus. We observed statistically significant differences in accuracy between Tandem R and Tandem E: y(Tandem E)= 1.05 x(Tandem R)+0.07 and between Tandem E and Prostatus: y(Prostatus)= 0.94 x(Tandem E)+0.02 In both comparisons prostate-specific antigen values ranged from 0-40 microg/l. Recalculation with both reference preparations did not solve these discrepancies. One exception was the combination Tandem R and Tandem E. The application of either reference preparation solved the differences in accuracy here. In conclusion, even after recalibration, assays for total prostate-specific antigen are still not completely interchangeable.