Studies have reported lower prostate specific antigen (PSA) levels in men with a higher body mass index (BMI). Additional factors such as diabetes mellitus, benign prostatic hyperplasia (BPH) and certain medications may also affect PSA levels and confound the PSA-BMI association. In this study we evaluated the potential confounding effect of these factors on the obesity-PSA relationship and evaluated the association between these factors and PSA level.
The study cohort consisted of 770 population-based controls without a history of prostate cancer (PCa) who participated in a prior PCa study. Demographic, anthropometric and medical history data were obtained, and PSA level was determined from blood drawn at the time of interview. Linear regression was performed to evaluate the PSA-BMI relationship, adjusting for potential confounders. Finally, a forward stepwise algorithm was used to determine which factors were independently associated with PSA values.
With increasing BMI (<25, 25–29, ≥30), the geometric mean PSA level declined (1.18, 1.13, and 0.94, respectively); obese men had a 17% (95% CI 0.70–0.99) lower age-adjusted PSA level compared to normal weight men. However, this relationship was non-significant (p=0.17) in the multivariate model. Independent predictors of PSA level included age (β=1.03, 95%CI 1.02–1.04), history of BPH (β=1.48, 95%CI 1.27–1.72), current statin (β=0.85, 95%CI 0.74–0.98) and NSAID use (β=0.84, 95%CI 0.72–0.98).
The relationship between obesity and PSA is confounded by a number of factors, which likely explain the observed inverse association previously reported. These results should help in interpreting PSA values in men screened for PCa.
Although prostate-specific antigen (PSA) serum level is currently the standard of care for prostate cancer screening in the United States, it lacks ideal specificity and additional biomarkers are needed to supplement or potentially replace serum PSA testing. Emerging evidence suggests that monitoring the noncoding RNA transcript PCA3 in urine may be useful in detecting prostate cancer in patients with elevated PSA levels. Here, we show that a multiplex panel of urine transcripts outperforms PCA3 transcript alone for the detection of prostate cancer. We measured the expression of seven putative prostate cancer biomarkers, including PCA3, in sedimented urine using quantitative PCR on a cohort of 234 patients presenting for biopsy or radical prostatectomy. By univariate analysis, we found that increased GOLPH2, SPINK1, and PCA3 transcript expression and TMPRSS2:ERG fusion status were significant predictors of prostate cancer. Multivariate regression analysis showed that a multiplexed model, including these biomarkers, outperformed serum PSA or PCA3 alone in detecting prostate cancer. The area under the receiver-operating characteristic curve was 0.758 for the multiplexed model versus 0.662 for PCA3 alone (P = 0.003). The sensitivity and specificity for the multiplexed model were 65.9% and 76.0%, respectively, and the positive and negative predictive values were 79.8% and 60.8%, respectively. Taken together, these results provide the framework for the development of highly optimized, multiplex urine biomarker tests for more accurate detection of prostate cancer.
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.
An English-language literature review of the Medline database (1990 to August 2010) of published data on blood-based biomarkers and PCa was undertaken.
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.
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.
Prostate neoplasms; molecular markers; prostate specific antigen
PSA and free PSA (fPSA) have limited specificity for detecting clinically significant, curable prostate cancer (PCa), leading to unnecessary biopsies and detection and treatment of some indolent tumors. [−2]proPSA (p2PSA) may improve specificity for detecting clinically significant PCa. Our objective was to evaluate p2PSA, fPSA, and PSA in a mathematical formula (prostate health index [phi] = [−2]proPSA / fPSA) × PSA1/2) to enhance specificity for detecting overall and high-grade PCa.
Materials and Methods
We enrolled 892 men in a prospective multi-institutional trial with no history of PCa, normal rectal examination, a PSA of 2–10 ng/mL, and ≥6- core prostate biopsy. We examined the relationship of serum PSA, %fPSA and phi with biopsy results. The primary endpoints were the specificity and AUC using phi to detect overall and Gleason ≥7 prostate cancer on biopsy compared with %fPSA.
For the 2–10 ng/mL PSA range, at 80–95% sensitivity, the specificity and AUC (0.703) of phi exceeded those of PSA and %fPSA. Increasing phi was associated with a 4.7-fold increased risk of PCa and 1.61-fold increased risk of Gleason ≥7 disease on biopsy. The AUC for phi (0.724) exceeded that of %fPSA (0.670) in discriminating between PCa with Gleason ≥ 4+3 vs. lower grade disease or negative biopsies. Phi results were not associated with age and prostate volume.
Phi may be useful in PCa screening to reduce unnecessary biopsies in men age ≥50 years with PSA 2–10 ng/mL and negative DRE, with minimal loss in sensitivity.
Elevated serum prostate-specific antigen (PSA) levels are predictive of a future diagnosis of prostate cancer. To test the hypothesis that older men with low PSA levels may require less intensive PSA testing because of a reduced prostate cancer detection rate, we evaluated the association between age, baseline PSA level, and prostate cancer detection.
We conducted a prospective cohort study among participants in a study of aging who had serial PSA measurements taken from age 60 or 65 years until they either were diagnosed with prostate cancer (cancer case subjects) or reached the age of 75 years (subjects without prostate cancer). The time of cancer detection among cancer case subjects was defined as the measurement date on which a PSA level above 4.0 ng/mL was detected (i.e., PSA conversion). Cancer case subjects and subjects without prostate cancer were analyzed according to baseline PSA level and age.
All cancer case subjects in the 60-year-old cohort had baseline PSA levels above 0.5 ng/mL, and 14 of 15 cancer cases that would have been detected by a PSA conversion among the 65-year-old cohort were associated with baseline PSA levels of 1.1 ng/mL or more. If PSA testing were discontinued in men aged 65 years with PSA levels of 0.5 ng/mL or less, 100% (95% confidence interval [CI] = 78%–100%) of the cancers would still be detected by age 75 years; if PSA testing were discontinued in men aged 65 years who had PSA levels of 1.0 ng/mL or less, 94% (95% CI = 70%–100%) of the cancers would still be detected by age 75 years.
These data suggest that a decrease in the intensity of screening among older men with low PSA values may not lead to an increase in undetected prostate cancer.
To determine whether higher intensity of prostate-specific antigen (PSA) surveillance was associated with earlier detection of biochemical recurrence (BCR) or survival.
Patients and Methods
We identified a population-based cohort of 832 men diagnosed with nonmetastatic prostate cancer between January 1, 1995, and July 31, 2006. These men were treated with radical prostatectomy (RP), brachytherapy or external beam radiation therapy (RT), or primary androgen deprivation therapy or chose watchful waiting. To test the associations of intensity in PSA surveillance with study outcomes, we used a 2-year landmark analysis to assess whether the number of PSA tests during the first 2 years after treatment was associated with earlier detection of BCR, prostate cancer–related mortality, and all-cause mortality. We used landmark analysis to assess the association of PSA intensity, adjusting for clinicopathologic covariate, with outcome.
Median follow-up time for the entire cohort was 6.7 years. Higher Gleason score was the only clinicopathologic variable associated with higher PSA frequency in multivariable analysis for both the RP and RT groups (P value of .001 and .05, respectively). After adjustment for other covariates, the frequency of PSA tests during the first 2 years after RP did not increase the ability to detect BCR (hazard ratio, 1.00; 95% confidence interval, 0.84-1.19) or all-cause mortality (hazard ratio, 0.95; 95% confidence interval, 0.70-1.30) in the landmark analysis.
Higher intensity of PSA surveillance during the 2 years after RP or RT did not improve earlier detection of BCR or survival. Evidence-based guidelines for PSA surveillance after primary treatment are needed.
ACM, all-cause mortality; ADT, androgen deprivation therapy; BCR, biochemical recurrence; HR, hazard ratio; PCSM, prostate cancer–specific mortality; PSA, prostatic-specific antigen; RP, radical prostatectomy; RT, radiation therapy; WW, watchful waiting
Background. Prostate-specific antigen (PSA) occurs in different molecular forms in serum: free PSA (fPSA) and complexed PSA (cPSA), the sum of which corresponds to total PSA (tPSA). In addition to tPSA, percent fPSA is widely used in the detection of prostate cancer. Free PSA, ∼28 kDa, is eliminated by glomerular filtration. Previous data showed that men with end-stage renal dysfunction requiring chronic dialysis have increased percent fPSA. In this study, we evaluated whether moderate-to-severe chronic renal dysfunction, but with no need for dialysis, also importantly affects percent fPSA.
Methods. The study group consisted of 101 men (median age 57 years, interquartile range 46–68) with chronic kidney disease and no diagnosis of prostate cancer. Their median glomerular filtration rate (GFR) was 23 mL/min/1.73 m2 (interquartile range 16–33; range 8–83), determined by iohexol clearance. Controls included 5264 men (median age 57 years, interquartile range 54–62) attending a prostate cancer screening program with no diagnosis of prostate cancer during 8 years of follow-up.
Results. With adjustment for age, median fPSA levels and percent fPSA were significantly higher (P < 0.001) in patients with renal dysfunction, 0.45 μg/L and 47.2%, respectively, compared to controls, 0.29 μg/L and 29.9%, respectively. Regression analysis in the study group showed a significant association between GFR and percent fPSA (P = 0.036).
Conclusions. The percent fPSA is importantly influenced by moderately impaired renal function in men with chronic kidney disease. For such men, use of the current clinical decision limits for percent fPSA could cause some men with prostate cancer to be misdiagnosed as having benign disease, and therefore fPSA should not be used to diagnose prostate cancer in these patients.
diagnosis; glomerular filtration rate; chronic kidney disease; prostate cancer; prostate-specific antigen
The American Cancer Society and American Urologic Association recommend prostate cancer screening for average-risk men between the ages of 50 and 75 years using digital rectal examination and prostate-specific antigen (PSA) testing. Measuring the percent free PSA may improve test specificity for detecting prostate cancer when the total PSA is between 2.5 and 10 ng/mL.
To assess whether free PSA testing practices are consistent with published screening guidelines.
Retrospective analysis of free PSA testing performed by a national reference laboratory between October 1, 2003 and September 30, 2004.
Free PSA and total PSA results and the age of the patient at testing.
Over 24% of free PSA tests were performed on patients greater than 75 years of age, and 38% were performed on patients with a total PSA either less than 2.5 ng/mL or greater than 10.0 ng/mL.
A substantial proportion of free PSA tests performed in a national reference laboratory appeared to be inconsistent with existing screening guidelines. This raises concern that some of these patients may have received inappropriate diagnostic workup and/or therapy, resulting in excess medical costs and potential harms.
utilization; mens'; health; cancer screening; guidelines
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.
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[en]6 due to elevated PSA.
Total, free, and intact PSA and human kallikrein 2 were measured for 1[en]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.
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.
cancer detection; predictive models; prostate biopsy; prostate cancer; prostate-specific antigen; PSA velocity
Associations of serum vitamin A and carotenoid levels with markers of prostate cancer detection were evaluated among 3927 U.S. men, 40–85 years of age, who participated in the 2001–2006 National Health and Nutrition Examination Surveys. Five recommended definitions of prostate cancer detection were adopted using total and free prostate specific antigen (tPSA and fPSA) laboratory measurements. Men were identified as high-risk based on alternative cut-offs, namely, tPSA>10 ng/ml, tPSA>4 ng/ml, tPSA> 2.5 ng/ml, %fPSA<25% and %fPSA<15%. %fPSA was defined as (fPSA÷tPSA)×100%. Serum levels of vitamin A (retinol, retinyl esters) and carotenoids (α-carotene, β-carotene, β-cryptoxanthin, lutein+zeaxanthin, lycopene) were defined as quartiles and examined as risk/protective factors for PSA biomarkers. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using binary logistic models. After adjustment for known demographic, socioeconomic and lifestyle confounders, high serum levels of retinyl esters (tPSA>10 ng/ml: Q4vs.Q1→OR=0.38, 95% CI: 0.14–1.00) and α-carotene (%fPSA<15%: Q4vs.Q1→OR=0.49, 95% CI: 0.32–0.76) were associated with a lower odds whereas high serum level of lycopene (tPSA>2.5 ng/ml: Q4vs.Q1→OR=1.49, 95% CI: 1.01–2.14) was associated with a greater odds of prostate cancer detection. Apart from the three significant associations observed, no other exposure-outcome association was significant. Monitoring specific antioxidant levels may be helpful in early detection of prostate cancer.
vitamin A; carotenoids; prostate cancer; prostate-specific antigen
Prostate cancer gene 3 (PCA3) encodes a prostate-specific messenger RNA (mRNA) that serves as the target for a novel urinary molecular assay for prostate cancer detection. Our objective is to evaluate the ability of PCA3 in addition to serum prostate-specific antigen (PSA) to predict cancer detection by extended template biopsy.
From September 2006 to December 2007, whole urine samples were collected after attentive digital rectal exam from 187 men prior to ultrasound-guided 12-core prostate biopsy in a urology outpatient clinic. Urine PCA3/PSA mRNA ratio scores were measured within one month and serum PSA within six months of biopsy. These were related to cancer positivity on biopsy.
Overall, 87/187 (46.5%) biopsies were positive for cancer. Sensitivity and specificity of PCA3 score ≥35 for positive biopsy were 52.9% and 80.0%; positive and negative predictive values were 69.7% and 66.1%. Using receiver operating characteristic curve (ROC) analysis, PSA alone resulted in an area under the curve (AUC) of 0.63 for prostate cancer detection; PSA + PCA3 score resulted in an AUC of 0.71. The likelihood of prostate cancer detection rose with increasing PCA3 score ranges (p>0.0001), providing possible PCA3 score parameters for stratification into low, moderate, high, and very high risk groups for biopsy positivity.
Adding PCA3 to serum PSA improves prostate cancer prediction. Use of PCA3 in a clinical setting may help risk-stratify patients for biopsy and cancer detection, although a large-scale validation study is needed to address assay standardization, optimal cut-off values and appropriate patient populations.
prostatic neoplasms; genes; biopsy; urine
There are still debates on the benefit of mass screening for prostate cancer (PCA) by prostate specific antigen (PSA) testing, and on systemized surveillance protocols according to PSA level. Furthermore, there is a paucity of literature on current practice patterns according to PSA level in the Korean urologic field. Here, we report the results of a nationwide, multicenter, retrospective chart-review study.
Materials and Methods
Overall 2122 Korean men (>40 years old, PSA >2.5 ng/mL) were included in our study (from 122 centers, in 2008). The primary endpoint was to analyze the rate of prostate biopsy according to PSA level. Secondary aims were to analyze the detection rate of PCA, the clinical features of patients, and the status of surveillance for PCA according to PSA level.
The rate of prostate biopsy was 7.1%, 26.3%, 54.2%, and 64.3% according to PSA levels of 2.5-3.0, 3.0-4.0, 4.0-10.0, and >10.0 ng/mL, respectively, and the PCA detection rate was 16.0%, 22.2%, 20.2%, and 59.6%, respectively. At a PSA level >4.0 ng/mL, we found a lower incidence of prostate biopsy in local clinics than in general hospitals (21.6% vs. 66.2%, respectively). A significant proportion (16.6%) of patients exhibited high Gleason scores (≥8) even in the group with low PSA values (2.5-4.0 ng/mL).
We believe that the results from this nationwide study might provide an important database for the establishment of practical guidelines for the screening and management of PCA in Korean populations.
Mass screening; prostate biopsy; prostate specific antigen
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.
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.
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.
The percent free prostate-specific antigen (PSA) may complement total PSA for prostate cancer screening, but is of no benefit for monitoring patients with previous prostate cancer diagnoses. At the Princess Margaret Hospital, a tertiary cancer centre in Toronto, Ontario, Canada, PSA values in the range 4 to 10 ng/mL prompt reflexive measurements of free PSA. We hypothesize that reflexive free PSA testing at tertiary cancer centres generates unnecessary costs as the test is often conducted on patients with previous diagnoses of prostate cancer.
Materials and Methods:
We reviewed all reflexive free PSA measurements conducted on a random sample of 250 men in a 10-year period at our institution. We determined the clinical indications for the PSA tests which triggered reflexive free PSA measurements to estimate the proportion of free PSA tests that are not clinically indicated.
We reviewed the 1099 reflexive free PSA measurements for the 250 subjects. Of these tests, 562 (51%) were triggered by PSA tests ordered for screening/early detection, and 537 (49%) for monitoring.
Of all reflexive free PSA tests, 49% were unnecessary. We conducted 3022 free PSA tests, at a cost of $5.84 per test (Can$); the tests were performed in 2009 at this institution for a total cost of $17 648.48, about 49% of which ($8647.76) likely represents unnecessary annual costs. We suggest a trial of user-selectable order sets allowing physicians to choose whether to include reflexive free PSA measurements on a case-by-case basis. This policy might improve the cost-effectiveness of the PSA test at tertiary cancer centres.
Previous studies describe decreased prostate cancer risk in HIV-infected men. In the U.S., prostate-specific antigen (PSA) screening is common and increases detection of prostate cancer. We evaluated whether the prostate cancer deficit among men with AIDS reflects differential PSA screening.
Data from the U.S. HIV/AIDS Cancer Match Study were used to calculate standardized incidence ratios (SIRs) for prostate cancer, comparing men with AIDS (N=287,247) to the general population. Further, we estimated PSA testing rates in the Johns Hopkins HIV Clinical Cohort.
Prostate cancer rates increased over time in the general population and beginning in the 1990s were consistently higher than among men with AIDS. Men with AIDS had the same prostate cancer risk as the general population in the pre-PSA era (<1992, SIR=1.00), but significantly reduced risk during the PSA era overall (1992–2007, SIR=0.50) and across age, race, HIV risk group, antiretroviral therapy era, and CD4 counts. Local and regional stage prostate cancer risk was lower among men with AIDS (SIRs 0.49 and 0.14, respectively), but distant stage cancer risk did not differ (SIR=0.85). Among HIV-infected men ≥40 years old, PSA testing was uncommon (18.7% per year), but increased 2.4-fold from 2000 to 2008, after age adjustment.
Prostate cancer risk was decreased by 50% among men with AIDS compared to the general population. This deficit was limited to the PSA era and early stage cancers.
Our findings suggest that the prostate cancer deficit in HIV-infected men is largely due to differential PSA screening.
Prostate cancer; HIV; PSA; AIDS; screening
The UK National Institute for Health and Clinical Excellence (NICE) guidance recommends conservative management of men with ‘low-risk' localised prostate cancer, monitoring the disease using prostate-specific antigen (PSA) kinetics and re-biopsy. However, there is little evidence of the changes in PSA level that should alert to the need for clinical re-assessment.
This study compares the alerts resulting from PSA kinetics and a novel longitudinal reference range approach, which incorporates age-related changes, during the monitoring of 408 men with localised prostate cancer. Men were monitored by regular PSA tests over a mean of 2.9 years, recording when a man's PSA doubling time fell below 2 years, PSA velocity exceeded 2 ng ml–1 per year, or when his upper 10% reference range was exceeded.
Prostate-specific antigen doubling time and PSA velocity alerted a high proportion of men initially but became unresponsive to changes with successive tests. Calculating doubling time using recent PSA measurements reduced the decline in response. The reference range method maintained responsiveness to changes in PSA level throughout the monitoring.
The increasing unresponsiveness of PSA kinetics is a consequence of the underlying regression model. Novel methods are needed for evaluation in cohorts currently being managed by monitoring. Meanwhile, the NICE guidance should be cautious.
disease management; kinetics; PSA; prostatic neoplasms
We developed and validated a nomogram which predicts presence of prostate cancer (PCa) on needle biopsy.
Materials and Methods
We used 3 cohorts of men who were evaluated with sextant biopsy of the prostate and whose presenting prostate specific antigen (PSA) was not greater than 50 ng/ml. Data from 4,193 men from Montreal, Canada were used to develop a nomogram based on age, digital rectal examination (DRE) and serum PSA. External validation was performed on 1,762 men from Hamburg, Germany. Data from these men were subsequently used to develop a second nomogram in which percent free PSA (%fPSA) was added as a predictor. External validation was performed using 514 men from Montreal. Both nomograms were based on multivariate logistic regression models. Predictive accuracy was evaluated with areas under the receiver operating characteristic curve and graphically with loess smoothing plots.
PCa was detected in 1,477 (35.2%) men from Montreal, 739 (41.9%) men from Hamburg and 189 (36.8%) men from Montreal. In all models all predictors were significant at 0.05. Using age, DRE and PSA external validation AUC was 0.69. Using age, DRE, PSA and %fPSA external validation AUC was 0.77.
A nomogram based on age, DRE, PSA and %fPSA can highly accurately predict the outcome of prostate biopsy in men at risk for PCa.
prostatic neoplasms; biopsy; nomograms; validation studies
Most data on prostate-specific antigen (PSA) testing come from urologic cohorts comprised of volunteers for screening programs. We evaluated the diagnostic accuracy of PSA testing for detecting prostate cancer in community practice.
PSA testing results were compared with a reference standard of prostate biopsy. Subjects were 2,620 men 40 years and older undergoing (PSA) testing and biopsy from 1/1/95 through 12/31/98 in the Albuquerque, New Mexico metropolitan area. Diagnostic measures included the area under the receiver-operating characteristic curve, sensitivity, specificity, and likelihood ratios.
Cancer was detected in 930 subjects (35%). The area under the ROC curve was 0.67 and the PSA cutpoint of 4 ng/ml had a sensitivity of 86% and a specificity of 33%. The likelihood ratio for a positive test (LR+) was 1.28 and 0.42 for a negative test (LR-). PSA testing was most sensitive (90%) but least specific (27%) in older men. Age-specific reference ranges improved specificity in older men (49%) but decreased sensitivity (70%), with an LR+ of 1.38. Lowering the PSA cutpoint to 2 ng/ml resulted in a sensitivity of 95%, a specificity of 20%, and an LR+ of 1.19.
PSA testing had fair discriminating power for detecting prostate cancer in community practice. The PSA cutpoint of 4 ng/ml was sensitive but relatively non-specific and associated likelihood ratios only moderately revised probabilities for cancer. Using age-specific reference ranges and a PSA cutpoint below 4 ng/ml improved test specificity and sensitivity, respectively, but did not improve the overall accuracy of PSA testing.
Prostatic neoplasms; prostate-specific antigen; sensitivity and specificity; ROC curve; likelihood functions
The degree of variability in prostate-specific antigen (PSA) measurements is important for interpreting test results in screening programs, and particularly for interpreting the significance of changes between repeated tests. This study aimed to determine the long-term intra-individual variation for PSA in healthy men.
A randomly selected cohort of men in a biennial prostate cancer screening program (ERSPC) conducted in Sweden from 1995–1996 to 2001–2002. We studied men who had total PSA (tPSA) levels <2.0 ng/ml in 2001–2002. This included 791 men with tPSA ≤ 0.61 ng/ml (group A), 1,542 men with tPSA ≤ 0.99 ng/ml (group B), and 1,029 men with tPSA 1.00–1.99 ng/ml (group C). The intra-individual variability of free PSA (fPSA) and tPSA was assessed by calculating coefficients of variation (CV) for each individual’s PSA measurements from the first and second round of screening (1995–1996 and 1997–1998).
Intra-individual CV (geometric means) for tPSA were 13.7%, 12.7%, and 11.5% in groups A, B, and C, respectively. Corresponding CVs for fPSA were significantly lower, ranging from 12.1% to 10.4%. The estimated biological variation of tPSA and fPSA in groups A to C were 12.5%, 11.4%, 10.0% and 9.7%, 7.8%, 7.5%, respectively.
In healthy men with PSA levels less than 2 ng/ml, the natural long-term variability for tPSA was less than 14%, and with 95% probability, a change in tPSA greater than 30% indicates a change beyond normal random variation.
PSA; biological variation; critical difference; screening
Most men with elevated levels of prostate-specific antigen (PSA) do not have prostate cancer, leading to a large number of unnecessary biopsies. A statistical model based on a panel of four kallikreins has been shown to predict the outcome of a first prostate biopsy. In this study, we apply the model to an independent data set of men with previous negative biopsy but persistently elevated PSA.
The study cohort consisted of 925 men with a previous negative prostate biopsy and elevated PSA (⩾3 ng ml−1), with 110 prostate cancers detected (12%). A previously published statistical model was applied, with recalibration to reflect the lower positive biopsy rates on rebiopsy.
The full-kallikrein panel had higher discriminative accuracy than PSA and DRE alone, with area under the curve (AUC) improving from 0.58 (95% confidence interval (CI): 0.52, 0.64) to 0.68 (95% CI: 0.62, 0.74), P<0.001, and high-grade cancer (Gleason ⩾7) at biopsy with AUC improving from 0.76 (95% CI: 0.64, 0.89) to 0.87 (95% CI: 0.81, 0.94), P=0.003). Application of the panel to 1000 men with persistently elevated PSA after initial negative biopsy, at a 15% risk threshold would reduce the number of biopsies by 712; would miss (or delay) the diagnosis of 53 cancers, of which only 3 would be Gleason 7 and the rest Gleason 6 or less.
Our data constitute an external validation of a previously published model. The four-kallikrein panel predicts the result of repeat prostate biopsy in men with elevated PSA while dramatically decreasing unnecessary biopsies.
prostate cancer; biomarkers; predictive value of tests; prostate-specific antigen; cancer screening
Due to the limited specificity of prostate-specific antigen (PSA) for prostate cancer (CaP) screening, there is an ongoing search for adjunctive biomarkers. Retrospective studies have suggested that an isoform of proenzyme PSA called [−2] proPSA (p2PSA) may enhance the specificity of PSA-based screening. The objective of our study was to examine the utility of p2PSA in a prospective CaP screening study.
Materials and Methods
From a population of 2034 men undergoing CaP screening, we examined the relationship between p2PSA and CaP detection. Specifically, we compared the utility of total PSA, the ratio of free PSA (fPSA) to total PSA (%fPSA), the ratio of p2PSA to fPSA (%p2PSA) and a formula combining PSA, fPSA and p2PSA (called Beckman Coulter prostate health index or phi®) to predict CaP among men from the study undergoing prostate biopsy with PSA levels of 2.5–10 ng/ml and non-suspicious digital rectal examination (DRE).
Despite similar total PSA levels (p=0.88), both %fPSA (p=0.02) and %p2PSA (p=0.0006) distinguished between positive and negative biopsy results. On receiver operating characteristic (ROC) analysis, %p2PSA (AUC 0.76) outperformed both PSA (AUC 0.50) and %fPSA (AUC 0.68) for differentiating between CaP and benign disease. Setting the sensitivity at 88.5%, p2PSA led to a substantial improvement in specificity, positive and negative predictive values. The Beckman Coulter phi® (AUC 0.77) had the best overall performance characteristics.
This is the first prospective study to demonstrate that p2PSA provides improved discrimination between CaP and benign disease in screened men with PSA levels from 2.5 to 10 ng/ml and negative DRE.
prostate-specific antigen; PSA; free PSA; PSA isoforms; proPSA
Objectives To measure the effect of the adverse events within 35 days of transrectal ultrasound guided biopsy from the perspective of asymptomatic men having prostate specific antigen (PSA) testing; to assess early attitude to re-biopsy; to estimate healthcare resource use associated with adverse events due to biopsy; and to develop a classification scheme for reporting adverse events after prostate biopsy.
Design Prospective cohort study (Prostate Biopsy Effects: ProBE) nested within Prostate Testing for Cancer and Treatment (ProtecT) study.
Participants Between 1999 and 2008, 227 000 community dwelling men aged 5069 years were identified at 352 practices and invited to counselling about PSA testing. 111 148 attended a nurse led clinic in the community, and 10 297 with PSA concentrations of 3-20 ng/mL were offered biopsy within ProtecT. Between February 2006 and May 2008, 1147/1753 (65%) eligible men (mean age 62.1 years, mean PSA 5.4 ng/mL) having 10 core transrectal ultrasound guided biopsy under antibiotic cover in the context of ProtecT were recruited to the ProBE study.
Outcome measures Purpose designed questionnaire administered at biopsy and 7 and 35 days after the procedure to measure frequency and effect of symptoms related to pain, infection, and bleeding; patients’ attitude to repeat biopsy assessed immediately after biopsy and 7 days later; participants’ healthcare resource use within 35 days of biopsy evaluated by questionnaire, telephone follow-up, and medical note review; each man’s adverse event profile graded according to symptoms and healthcare use.
Results Pain was reported by 429/984 (43.6%), fever by 172/985 (17.5%), haematuria by 642/976 (65.8%), haematochezia by 356/967 (36.8%), and haemoejaculate by 605/653 (92.6%) men during the 35 days after biopsy. Fewer men rated these symptoms as a major/moderate problem—71/977 (7.3%) for pain, 54/981 (5.5%) for fever, 59/958 (6.2%) for haematuria, 24/951 (2.5%) for haematochezia, and 172/646 (26.6%) for haemoejaculate. Immediately after biopsy, 124/1142 (10.9%, 95% confidence interval 9.2 to 12.8) men reported that they would consider further biopsy a major or moderate problem: seven days after biopsy, this proportion had increased to 213/1085 (19.6%, 17.4% to 22.1%). A negative attitude to repeat biopsy was associated with unfavourable experience after the first biopsy, particularly pain at biopsy (odds ratio 8.2, P<0.001) and symptoms related to infection (7.9, P<0.001) and bleeding (4.2, P<0.001); differences were evident between centres (P<0.001). 119/1147 (10.4%, 8.7% to 12.3%) men reported consultation with a healthcare professional (usually their general practitioner), most commonly for infective symptoms. Complete data for all index symptoms at all time points were available in 851 participants. Symptoms and healthcare use could be used to grade these men as follows: grade 0 (no symptoms/contact) 18 (2.1%, 1.3% to 3.3%); grade 1 (minor problem/no contact) 550 (64.6%, 61.4% to 67.8%); grade 2 (moderate/major problem or contact) 271 (31.8%, 28.8% to 35.1%); grade 3 (hospital admission) 12 (1.4%, 0.8% to 2.4%); and grade 4 (death) 0. Grade of adverse event was associated with an unfavourable attitude to repeat biopsy (Kendall’s τ-b ordinal by ordinal 0.29, P<0.001).
Conclusion This study with a high response rate of 89% at 35 days in men undergoing biopsy in the context of a randomised controlled trial has shown that although prostate biopsy is well tolerated by most men, it is associated with significant symptoms in a minority and affects attitudes to repeat biopsy and primary care resource use. These findings will inform men who seek PSA testing for detection of prostate cancer and assist their physicians during counselling about the potential risks and effect of biopsy. Variability in the adverse event profile between centres suggests that patients’ outcomes could be improved and healthcare use reduced with more effective administration of local anaesthetic and antibiotics.
Trial registration Current Controlled Trials ISRCTN20141297.
Prostate-specific antigen (PSA) is widely used to detect prostate cancer. The low positive predictive value of elevated PSA results in large numbers of unnecessary prostate biopsies. We set out to determine whether a multivariable model including four kallikrein forms (total, free, and intact PSA, and human kallikrein 2 (hK2)) could predict prostate biopsy outcome in previously unscreened men with elevated total PSA.
The study cohort comprised 740 men in Göteborg, Sweden, undergoing biopsy during the first round of the European Randomized study of Screening for Prostate Cancer. We calculated the area-under-the-curve (AUC) for predicting prostate cancer at biopsy. AUCs for a model including age and PSA (the 'laboratory' model) and age, PSA and digital rectal exam (the 'clinical' model) were compared with those for models that also included additional kallikreins.
Addition of free and intact PSA and hK2 improved AUC from 0.68 to 0.83 and from 0.72 to 0.84, for the laboratory and clinical models respectively. Using a 20% risk of prostate cancer as the threshold for biopsy would have reduced the number of biopsies by 424 (57%) and missed only 31 out of 152 low-grade and 3 out of 40 high-grade cancers.
Multiple kallikrein forms measured in blood can predict the result of biopsy in previously unscreened men with elevated PSA. A multivariable model can determine which men should be advised to undergo biopsy and which might be advised to continue screening, but defer biopsy until there was stronger evidence of malignancy.
There is no available evidence from randomized trials that early detection of prostate cancer improves health outcomes, but the prostate-specific antigen (PSA) test is commonly used to screen men for prostate cancer.
The objective of the study is to see if screening with PSA decreases mortality from prostate cancer.
Design, setting, and participants
This is a case-control study using one-to-one matching on race, age, and time of availability of exposure to PSA screening. Decedents, 380, from New Jersey Vital Statistics 1997 to 2000 inclusive, 55–79 years of age at diagnosis were matched to living controls without metastatic prostate cancer. Medical records were obtained from all providers, and we abstracted information about PSA tests from 1989 to the time of diagnosis in each index case.
Measurements consist of a comparison of screening (yes, no) between cases and controls. Measure of association was the odds ratio.
Eligible cases were diagnosed each year from 1989 to 1999 with the median year being 1993. PSA screening was evident in 23.2–29.2% of cases and 21.8–26.1% of controls depending on the screening criteria. The unadjusted, matched odds ratio for dying of prostate cancer if ever screened was 1.09 (95% CI 0.76 to 1.60) for the most restrictive criteria and 1.19 (95% CI, 0.85 to 1.66) for the least restrictive. Adjustment for comorbidity and education level made no significant differences in these values. There were no significant interactions by age or race.
PSA screening using an ever/never tabulation for tests from 1989 until 2000 did not protect New Jersey men from prostate cancer mortality.
prostate cancer; screening; prostate specific antigen
“Race-specific” PSA needs evaluation in men at high-risk for prostate cancer (PCA) for optimizing early detection. Baseline PSA and longitudinal prediction for PCA was examined by self-reported race and genetic West African (WA) ancestry in the Prostate Cancer Risk Assessment Program, a prospective high-risk cohort.
Materials and Methods
Eligibility criteria are age 35–69 years, FH of PCA, African American (AA) race, or BRCA1/2 mutations. Biopsies have been performed at low PSA values (<4.0 ng/mL). WA ancestry was discerned by genotyping 100 ancestry informative markers. Cox proportional hazards models evaluated baseline PSA, self-reported race, and genetic WA ancestry. Cox models were used for 3-year predictions for PCA.
646 men (63% AA) were analyzed. Individual WA ancestry estimates varied widely among self-reported AA men. “Race-specific” differences in baseline PSA were not found by self-reported race or genetic WA ancestry. Among men with ≥ 1 follow-up visit (405 total, 54% AA), three-year prediction for PCA with a PSA of 1.5–4.0 ng/mL was higher in AA men with age in the model (p=0.025) compared to EA men. Hazard ratios of PSA for PCA were also higher by self-reported race (1.59 for AA vs. 1.32 for EA, p=0.04). There was a trend for increasing prediction for PCA with increasing genetic WA ancestry.
“Race-specific” PSA may need to be redefined as higher prediction for PCA at any given PSA in AA men. Large-scale studies are needed to confirm if genetic WA ancestry explains these findings to make progress in personalizing PCA early detection.
genetics, population; mass screening; African Americans; prostatic neoplasms