Prostate Specific Antigen Assay Standardization Bias Could Affect Clinical Decision Making

Challenges and Opportunities of Genomic Approaches in Therapeutics Development

The magnitude of all therapeutic responses is significantly determined by genome structure, variation, and functional interactions. This determination occurs at many levels which are discussed in the current review. Well-established examples of structural variation between individuals are known to dictate an individual's response to numerous drugs, as clearly illustrated by warfarin. The exponential rate of genomic-based interrogation is coupled with an expanding repertoire of genomic technologies and applications. This is leading to an ever more sophisticated appreciation of how structural variation, regulation of transcription and genomic structure, both individually and collectively, define cell therapeutic responses.

PSA kinetics before 40 years of age

Purpose:

The baseline PSA has been proposed as a possible marker for prostate cancer. The PSA determination before 40 years seems interesting because it not suffers yet the drawbacks related to more advanced ages. Considering the scarcity of data on this topic, an analysis of PSA kinetics in this period seems interesting.

Materials and Methods:

A retrospective assay in a database of a private diagnostic center was performed from 2003 to 2016. All subjects with a PSA before 40 years were included.

Results:

92995 patients performed PSA between the ages of 21 – 39. The mean value ranged from 0.66 ng / mL (at age 22) to 0.76 ng / mL (at age 39) and the overall mean was 0.73 ng / mL. As for outliers, 3783 individuals presented a baseline PSA > 1.6 ng / mL (p95). A linear regression model showed that each year there is a PSA increase of 0.0055 ng / mL (β = 0.0055; r² = 0.0020; p < 0.001). A plateau in PSA between 23 and 32 years was found and there were only minimal variations among the ages regardless of the evaluated percentile.

Conclusion:

It was demonstrated that PSA kinetics before 40 years is a very slow and progressive phenomenon regardless of the assessed percentile. Considering our results, it could be suggested that any PSA performed in this period could represent the baseline value without significant distortions.

Biomarkers for Prostate Biopsy and Risk Stratification of Newly Diagnosed Prostate Cancer Patients

INTRODUCTION

Many new markers are now available as an aid for decisions about prostate biopsy for men without prostate cancer, and/or to improve risk stratification for men with newly diagnosed prostate cancer.

METHODS

A literature review was performed on currently available markers for use in decisions about prostate biopsy and initial prostate cancer treatment.

RESULTS

Although total prostate-specific antigen cutoffs were traditionally used for biopsy decisions, PSA elevations are not specific. Repeating the PSA test, and adjusting for factors like age, prostate volume and changes over time can increase specificity for biopsy decisions. The Prostate Health Index (phi) and 4K Score are new PSA-based markers that can be offered as second-line tests to decide on initial or repeat prostate biopsy. The PCA3 urine test and ConfirmMDx tissue test are additional options for repeat biopsy decisions. For men with newly diagnosed prostate cancer, genomic tests are available to refine risk classification and may influence treatment decisions.

CONCLUSIONS

Numerous secondary testing options are now available that can be offered to patients deciding whether to undergo prostate biopsy and those with newly diagnosed prostate cancer.

Screening for Cervical, Prostate, and Breast Cancer: Interpreting the Evidence

Cancer screening is an important component of prevention and early detection in public health and clinical medicine. The evidence for cancer screening, however, is often contentious. A description and explanation of disagreements over the evidence for cervical, breast, and prostate screening may assist physicians, policymakers, and citizens faced with screening decisions and suggest directions for future screening research. There are particular issues to be aware of in the evidence base for each form of screening, which are summarized in this paper. Five tensions explain existing conflicts over the evidence: (1) data from differing contexts may not be comparable; (2) screening technologies affect evidence quality, and thus evidence must evolve with changing technologies; (3) the quality of evidence of benefit varies, and the implications are contested; (4) evidence about harm is relatively new, there are gaps in that evidence, and there is disagreement over what it means; and (5) evidence about outcomes is often poorly communicated. The following principles will assist people to evaluate and use the evidence: (1) attend closely to transferability; (2) consider the influence of technologies on the evidence base; (3) query the design of meta-analyses; (4) ensure harms are defined and measured; and (5) improve risk communication practices. More fundamentally, there is a need to question the purpose of cancer screening and the values that inform that purpose, recognizing that different stakeholders may value different things. If implemented, these strategies will improve the production and interpretation of the methodologically challenging and always-growing evidence for and against cancer screening.

Prospective multicenter evaluation of the Beckman Coulter Prostate Health Index using WHO calibration

PURPOSE

Reported prostate specific antigen values may differ substantially among assays using Hybritech® or WHO standardization. The Beckman Coulter® Prostate Health Index and [-2]proPSA are newly approved serum markers associated with prostate cancer risk and aggressiveness. We studied the influence of assay standardization on these markers.

MATERIALS AND METHODS

Prostate specific antigen, percent free prostate specific antigen and [-2]proPSA were measured using Hybritech calibration in 892 men from a prospective, multicenter study undergoing prostate biopsy. We calculated the Prostate Health Index using the equation, ([-2]proPSA/free prostate specific antigen) × PSA. Index performance characteristics for prostate cancer detection were then determined using recalculated WHO calibration prostate specific antigen values.

RESULTS

The median Prostate Health Index was significantly higher in men with prostate cancer than in those with negative biopsies using WHO values (47.4 vs 39.8, p <0.001). The index offered improved discrimination of prostate cancer detection on biopsy (AUC 0.704) compared to percent free or total prostate specific antigen using the WHO calibration.

CONCLUSIONS

The Prostate Health Index can be calculated using Hybritech or WHO standardized assays. It significantly improved prediction of the biopsy outcome over that of percent free or prostate specific antigen alone.

Comprehensive analysis of post-diagnostic prostate-specific antigen kinetics as predictor of a prostate cancer progression in active surveillance patients

WHAT'S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD?: A significant proportion of patients diagnosed with prostate cancer do not require immediate treatment and could be managed by active surveillance, which usually includes serial measurements of prostate-specific antigen (PSA) levels and regular biopsies. The rate of rise in PSA levels, which could be calculated as PSA velocity or PSA doubling time, was previously suggested to be associated with the biological aggressiveness of prostate cancer. Although these parameters are obvious candidates for predicting tumour progression in active surveillance patients, earlier studies that examined this topic provided conflicting results. Our analysis showed that PSA velocity and PSA doubling time calculated at different time-points, by different methods, over different intervals, and in different sub-groups of active surveillance patients provide little if any prognostic information. Although we found some significant associations between PSA velocity and the risk of progression as determined by biopsy, the actual clinical significance of this association was small. Furthermore, PSA velocity did not add to the predictive accuracy of total PSA.

OBJECTIVE

To study whether prostate-specific antigen (PSA) velocity (PSAV) and PSA doubling time (PSADT) are associated with biopsy progression in patients managed by active surveillance.

PATIENTS AND METHODS

Our inclusion criteria for active surveillance are biopsy Gleason sum <7, two or fewer positive biopsy cores, ≤20% tumour present in any core, and clinical stage T1-T2a. Changes in any of these parameters during the follow-up that went beyond these limits are considered to be progression. This study included 250 patients who had at least one surveillance biopsy, an available PSA measured no earlier than 3 months before diagnosis, and at least one PSA measurement before each surveillance biopsy. We evaluated the association between PSA kinetics and progression at successive surveillance biopsies in different sub-groups of patients by calculating the area under the curve (AUC) as well as sensitivity and specificity of different thresholds.

RESULTS

Over a median follow-up of 3.0 years, the disease of 64 (26%) patients progressed. PSADT was not associated with biopsy progression, whereas PSAV was only weakly associated with progression in certain sub-groups. However, incorporation of PSAV in models including total PSA resulted in a moderate increase in AUC only when the entire cohort was analysed. In other sub-groups the predictive accuracy of total PSA was not significantly improved by adding PSAV.

CONCLUSIONS

Our findings confirm that PSA kinetics should not be used in decision-making in patients with low-risk prostate cancer managed by active surveillance. Regular surveillance biopsies should remain as the principal method of monitoring cancer progression in these men.

Sauver JL, Klee GG, Girman CJ, Lieber MM. Sixteen-year longitudinal changes in serum prostate-specific antigen levels: the olmsted county study

OBJECTIVE

To determine the distribution of longitudinal changes in serum prostate-specific antigen (PSA) levels from a population-based sample of men.

PATIENTS AND METHODS

In this prospective cohort study, a random sample of Olmsted County, Minnesota, men aged 40 to 79 years in 1990 were followed up biennially from January 1, 1990, through August 29, 2007. Serum PSA levels were determined at each examination, and men were censored for follow-up with a diagnosis of prostate cancer or treatment for benign prostatic hyperplasia. The empirical distributions of annual percent change and annual absolute change in serum PSA level were calculated and tabulated, including the median and 75th and 95th percentiles.

RESULTS

For men with PSA measurements 2 years apart, the median annual percent change in serum PSA level was 4.83% and the 95th percentile was about 49.76%. The variability in estimated annual change decreased with increasing time between assessments, with a 95th percentile of 21.82% after 8 or more years between assessments. Although the median absolute change per year increased with increasing age, the median percent change per year was fairly consistent across age groups.

CONCLUSION

These data demonstrate that, with shorter intervals between assessments, greater variability should be expected. These distributions should prove helpful to patients and clinicians in interpreting changes in serum PSA levels observed in typical clinical practices.

Understanding fragmentation of prostate cancer survivorship care: implications for cost and quality

BACKGROUND

Cancer survivors are particularly prone to the effects of a fragmented health care delivery system. The implications of fragmented cancer care across providers likely include greater spending and worse quality of care. For this reason, the authors measured relations between increasing fragmentation of cancer care, expenditures, and quality of care among prostate cancer survivors.

METHODS

A total of 67,736 patients diagnosed with prostate cancer between 1992 and 2005 were identified using Surveillance, Epidemiology, and End Results (SEER)-Medicare data. Using the Herfindahl-Hirschman Index and a measure of the average number of prostate cancer providers over time, patients were sorted into 3 fragmentation groups (low, intermediate, and high). The authors then examined annual per capita survivorship expenditures and a measure of quality (ie, repetitive prostate-specific antigen [PSA] testing within 30 days) according to their fragmentation exposure using multinomial logistic regression.

RESULTS

Patients with highly fragmented cancer care tended to be younger, white, and of higher socioeconomic status (all P < .001). Prostate cancer survivorship interventions were most common among patients with the highest fragmentation of care across providers (P < .001). After adjustment for clinical characteristics and prostate cancer survivorship interventions, higher degrees of fragmentation continued to be associated with repetitive PSA testing (13.6% for high vs 7.0% for low fragmentation; P < .001) and greater spending, particularly among patients not treated with androgen deprivation therapy.

CONCLUSIONS

Fragmented prostate cancer survivorship care is expensive and associated with potentially unnecessary services. Efforts to improve care coordination via current policy initiatives, electronic medical records, and the implementation of cancer survivorship tools may help to decrease fragmentation of care and mitigate downstream consequences for prostate cancer survivors.

Baseline prostate-specific antigen testing at a young age

CONTEXT

Prostate cancer screening is highly controversial, including the age to begin prostate-specific antigen (PSA) testing. Several studies have evaluated the usefulness of baseline PSA measurements at a young age.

OBJECTIVE

Review the literature on baseline PSA testing at a young age (≤60 yr) for the prediction of prostate cancer risk and prognosis.

EVIDENCE ACQUISITION

PubMed was searched for English-language publications on baseline PSA and prostate cancer for the period ending April 2011.

EVIDENCE SYNTHESIS

In most published series, median PSA levels in the general male population range from approximately 0.4 to 0.7 ng/ml in men in their 40s and from approximately 0.7 to 1.0 ng/ml in men in their 50s. Evidence from both nonscreening and screening populations has demonstrated the predictive value of a single baseline PSA measurement for prostate cancer risk assessment. Specifically, men with baseline PSA levels above the age-group-specific median have a greater risk of prostate cancer diagnosis during the next 20-25 yr. Additional studies confirmed that higher baseline PSA levels at a young age are also associated with a greater risk of aggressive disease, metastasis, and disease-specific mortality many years later.

CONCLUSIONS

Baseline PSA measurements at a young age are significant predictors of later prostate cancer diagnosis and disease-specific outcomes. Thus baseline PSA testing may be used for risk stratification and to guide screening protocols.

A multicenter study of [-2]pro-prostate specific antigen combined with prostate specific antigen and free prostate specific antigen for prostate cancer detection in the 2.0 to 10.0 ng/ml prostate specific antigen range

PURPOSE

Prostate specific antigen and free prostate specific antigen have limited specificity to detect clinically significant, curable prostate cancer, leading to unnecessary biopsy, and detection and treatment of some indolent tumors. Specificity to detect clinically significant prostate cancer may be improved by [-2]pro-prostate specific antigen. We evaluated [-2]pro-prostate specific antigen, free prostate specific antigen and prostate specific antigen using the formula, ([-2]pro-prostate specific antigen/free prostate specific antigen × prostate specific antigen(1/2)) to enhance specificity to detect overall and high grade prostate cancer.

MATERIALS AND METHODS

We enrolled 892 men with no history of prostate cancer, normal rectal examination, prostate specific antigen 2 to 10 ng/ml and 6-core or greater prostate biopsy in a prospective multi-institutional trial. We examined the relationship of serum prostate specific antigen, free-to-total prostate specific antigen and the prostate health index with biopsy results. Primary end points were specificity and AUC using the prostate health index to detect overall and Gleason 7 or greater prostate cancer on biopsy compared with those of free-to-total prostate specific antigen.

RESULTS

In the 2 to 10 ng/ml prostate specific antigen range at 80% to 95% sensitivity the specificity and AUC (0.703) of the prostate health index exceeded those of prostate specific antigen and free-to-total prostate specific antigen. An increasing prostate health index was associated with a 4.7-fold increased risk of prostate cancer and a 1.61-fold increased risk of Gleason score greater than or equal to 4 + 3 = 7 disease on biopsy. The AUC of the index exceeded that of free-to-total prostate specific antigen (0.724 vs 0.670) to discriminate prostate cancer with Gleason 4 or greater + 3 from lower grade disease or negative biopsy. Prostate health index results were not associated with age and prostate volume.

CONCLUSIONS

The prostate health index may be useful in prostate cancer screening to decrease unnecessary biopsy in men 50 years old or older with prostate specific antigen 2 to 10 ng/ml and negative digital rectal examination with minimal loss in sensitivity.

Prostate-specific antigen velocity for early detection of prostate cancer: result from a large, representative, population-based cohort

BACKGROUND

It has been suggested that changes in prostate-specific antigen (PSA) over time (ie, PSA velocity [PSAV]) aid prostate cancer detection. Some guidelines do incorporate PSAV cut points as an indication for biopsy.

OBJECTIVE

To evaluate whether PSAV enhances prediction of biopsy outcome in a large, representative, population-based cohort.

DESIGN, SETTING, AND PARTICIPANTS

There were 2742 screening-arm participants with PSA <3 ng/ml at initial screening in the European Randomized Study of Screening for Prostate Cancer in Rotterdam, Netherlands, or Göteborg, Sweden, and who were subsequently biopsied during rounds 2-6 due to elevated PSA.

MEASUREMENTS

Total, free, and intact PSA and human kallikrein 2 were measured for 1-6 screening rounds at intervals of 2 or 4 yr. We created logistic regression models to predict prostate cancer based on age and PSA, with or without free-to-total PSA ratio (%fPSA). PSAV was added to each model and any enhancement in predictive accuracy assessed by area under the curve (AUC).

RESULTS AND LIMITATIONS

PSAV led to small enhancements in predictive accuracy (AUC of 0.569 vs 0.531; 0.626 vs 0.609 if %fPSA was included), although not for high-grade disease. The enhancement depended on modeling a nonlinear relationship between PSAV and cancer. There was no benefit if we excluded men with higher velocities, which were associated with lower risk. These results apply to men in a screening program with elevated PSA; men with prior negative biopsy were not evaluated in this study.

CONCLUSIONS

In men with PSA of about ≥3 ng/ml, we found little justification for formal calculation of PSAV or for use of PSAV cut points to determine biopsy. Informal assessment of PSAV will likely aid clinical judgment, such as a sudden rise in PSA suggesting prostatitis, which could be further evaluated before biopsy.

Early prostate-specific antigen changes and the diagnosis and prognosis of prostate cancer

PURPOSE OF REVIEW

To delineate how recent findings on prostate-specific antigen (PSA) can improve prediction of risk, detection, and prediction of clinical endpoints of prostate cancer (PCa).

RECENT FINDINGS

The widely used PSA cut-point of 4.0 ng/ml increasingly appears arbitrary, but no cut-point achieves both high sensitivity and high specificity. The accuracy of detecting PCa can be increased by additional predictive factors and a combinations of markers. Evidence implies that a panel of kallikrein markers improves the specificity and reduces costs by eliminating unnecessary biopsies. Large, population-based studies have provided evidence that PSA can be used to predict PCa risk many years in advance, improve treatment selection and patient care, and predict the risk of complications and disease recurrence. However, definitive evidence is currently lacking as to whether PSA screening lowers PCa -specific mortality.

SUMMARY

PSA is still the main tool for early detection, risk stratification, and monitoring of PCa. However, PSA values are affected by many technical and biological factors. Instead of using a fixed PSA cut-point, using statistical prediction models and considering the integration additional markers may be able to improve and individualize PCa diagnostics. A single PSA measurement at early middle age can predict risk of advanced PCa decades in advance and stratify patients for intensity of subsequent screening.

Prostate-specific antigen-based screening for prostate cancer in the third millennium: useful or hype?

Prostate cancer is the most prevalent malignancy in men and the third leading cause of cancer deaths worldwide. Although the wide-spread introduction of total prostate-specific antigen (tPSA) testing has revolutionized the approach to the managed care of this disease, there are some biological, analytical, clinical, and economical issues that argue against the cost-effectiveness of tPSA-based population screening for early identification of cancer. The on-going standardization/harmonization efforts, along with the outcomes of recent epidemiological investigations, demonstrate that the current tPSA thresholds might be revised and possibly recalculated according to several demographical variables, such as age, ethnicity, genotype, family history, and body mass index. A major shortcoming of tPSA screening is the lack of reliable evidences of reduction in prostate cancer-associated mortality, due to the large lead-time because of the indolent growth rate, the impossibility to differentiate high-grade from indolent cancers, and the treatment-associated morbidity. Since no single tPSA cut-off was proven able to efficiently identify men at higher risk of death, the jeopardy of over-diagnosis and over-treatment is also tangible. The large expenditure is an additional source of concern. Finally, a wide-spread population screening also carries several ethical, social, and psychological implications, which might overwhelm the potential benefits.