LEVEL OF EVIDENCE:
2b. What's known on the subject? and What does the study add? In recent years, several nomograms were developed in an effort to decrease the number of unnecessary prostate biopsies. The European SWOP-PRI and the North American PCPT are among the most popular. However, evidence on the relative predictive accuracy is lacking. A head-to-head comparison on the diagnostic accuracy of two previously validated prostate cancer risk predictors on biopsy confirmed the superiority of these tools over PSA alone. Moreover, in the studied population, the European SWOP-PRI proved to be more accurate than the North American PCPT-CRC.
OBJECTIVE:
To compare the diagnostic accuracy of two previously validated prostate cancer risk predictors on biopsy.
PATIENTS AND METHODS:
In total, 390 consecutive patients submitted to 10-core systematic transrectal prostate biopsy at our institution were included in this retrospective study. External validation of a European (European Randomized Study of Screening for Prostate Cancer derived Prostate Risk Indicator; SWOP-PRI) and a North American (Prostate Cancer Prevention Trial Cancer Risk Calculator; PCPT-CRC) nomogram was performed. The predictive accuracy of these online available nomograms was calculated based on the area under the curve derived from receiver-operator characteristic curves and then compared using the DeLong method.
RESULTS:
Both tools were confirmed to be superior to prostate-specific antigen alone. Moreover, the SWOP-PRI (77.9%) displays a 7.96% increase in the predictive accuracy compared to the PCPT-CRC (69.9%) in a statistically significant fashion (P=0.002).
CONCLUSIONS:
The results obtained in the present study confirm the utility of nomograms with respect to biopsy outcome prediction in patients with suspicion of prostate cancer. In the current sample of patients, the European-based nomogram appears to be more accurate than the North American nonogram, which lacks information regarding prostate volume and prostatic ultrasonographic lesions. • To our knowledge, this is the first study to compare the accuracy of these popular risk calculators in a specific population

Carvalho, AP

Marques, V

Oliveira, M

Santos, A

English

Institutional repository of Hospital de Braga

©   2 0 1 0  T H E  A U T H O R S 1 7 8 0 B J U  I N T E R N A T I O N A L   ©   2 0 1 0  B J U  I N T E R N A T I O N A L  |  1 0 7 ,  1 7 8 0 – 1 7 8 3  |  doi:10.1111/j.1464-410X.2010.09727.x  2010 THE AUTHORS; BJU INTERNATIONAL  2010 BJU INTERNATIONALUrological OncologyONLINE NOMOGRAMS FOR PROSTATE BIOPSY OUTCOMEOLIVEIRA ET AL.Head-to-head comparison of two online nomograms for prostate biopsy outcome prediction Mário Oliveira, Vera Marques, António Pedro Carvalho and Américo Santos Department of Urology, Hospital de Braga, Braga, Portugal Accepted for publication 17 June 2010 and then compared using the DeLong method. RESULTS • Both tools were confirmed to be superior to prostate-specific antigen alone. Moreover, the SWOP-PRI (77.9%) displays a 7.96% increase in the predictive accuracy compared to the PCPT-CRC (69.9%) in a statistically significant fashion ( P   =  0.002). CONCLUSIONS • The results obtained in the present study confirm the utility of nomograms with respect to biopsy outcome prediction in patients with suspicion of prostate cancer.• In the current sample of patients, the European-based nomogram appears to be more accurate than the North American nonogram, which lacks information regarding prostate volume and prostatic ultrasonographic lesions.• To our knowledge, this is the first study to compare the accuracy of these popular risk calculators in a specific population.KEYWORDS biopsy, prostate cancer, nomogramStudy Type – Diagnosis (exploratory cohort)Level of Evidence 2b OBJECTIVE • To compare the diagnostic accuracy of two previously validated prostate cancer risk predictors on biopsy. PATIENTS AND METHODS • In total, 390 consecutive patients submitted to 10-core systematic transrectal prostate biopsy at our institution were included in this retrospective study.• External validation of a European (European Randomized Study of Screening for Prostate Cancer derived Prostate Risk Indicator; SWOP-PRI) and a North American (Prostate Cancer Prevention Trial Cancer Risk Calculator; PCPT-CRC) nomogram was performed.• The predictive accuracy of these online available nomograms was calculated based on the area under the curve derived from receiver–operator characteristic curves  INTRODUCTION In recent years, several nomograms have become available to the clinician, assisting in the risk stratification of prostate cancer (PCa) at needle biopsy [1–5]. On the basis of data obtained from large populations, these tools were developed for application in the daily clinical practice. However, and despite having shown a better predictive accuracy compared to PSA alone [6], the use of nomograms in the decision to perform prostate biopsy is not yet a standard practice [7].On the other hand, different variables are considered in the various nomograms that may contribute to their individual predictive accuracy. In addition to increased PSA, several positive predictors of PCa were identified, including a suspicious DRE and TRUS as well as a positive family history, whereas an increased prostate volume was considered a negative predictor [8]. Moreover, the accuracy of such tools may differ according to the characteristics of the target population [9,10].We considered it of interest to perform an external validation and compare the diagnostic accuracy of two popular online available risk calculators in a specific population: the European Randomized Study of Screening for Prostate Cancer derived Prostate Risk Indicator (SWOP-PRI) [1] and the Prostate Cancer Prevention Trial derived Cancer Risk Calculator (PCPT-CRC) [2]. PATIENTS AND METHODS PATIENT POPULATIONRetrospective analysis of data from consecutive patients submitted to 10-core systematic TRUS-guided prostate biopsy at our institution between January 2007 and August 2009 was performed. Patients were referred to biopsy as a result of either a suspicious DRE and/or elevated PSA. Analysis targeted subjects with a PSA level  < 50 ng/mL.BJUI B J U  I N T E R N A T I O N A L What’s known on the subject? and What does the study add? In recent years, several nomograms were developed in an effort to decrease the number of unnecessary prostate biopsies. The European SWOP-PRI and the North American PCPT are among the most popular. However, evidence on the relative predictive accuracy is lacking.A head-to-head comparison on the diagnostic accuracy of two previously validated prostate cancer risk predictors on biopsy confirmed the superiority of these tools over PSA alone. Moreover, in the studied population, the European SWOP-PRI proved to be more accurate than the North American PCPT-CRC. O N L I N E  N O M O G R A M S  F O R  P R O S T A T E  B I O P S Y  O U T C O M E ©   2 0 1 0  T H E  A U T H O R SB J U  I N T E R N A T I O N A L   ©  2 0 1 0  B J U  I N T E R N A T I O N A L 1 7 8 1 TRUS-GUIDED PROSTATE BIOPSYTRUS-guided prostate biopsy was performed using a 7-MHz probe (Prosound SSD-35005v, Aloka co. Ltd., Tokyo, Japan). An automatic biopsy gun (Porgés Laboratories, Le Plessis Robinson, France) with a 18-gauge needle (Coloplast Corporate, Humlebaek, Denmark) was used to obtain 10-core fragments.RISK CALCULATORSThe European SWOP-PRI was designed based on data obtained from 6288 Dutch males, mostly Caucasian, participating in a study on the viability of a population-based screening and its effect on mortality [1]. On the other hand, the North-American PCPT-CRC was based on data obtained from 5519 males from the placebo group of the study evaluating the possible preventive effect of finasteride in PCa development [2]. In both populations, sextant biopsies were performed.To obtain risk estimates, predictor variables necessary for each tool were gathered. Predictor variables considered for the SWOP-PRI nomogram included abnormalities on DRE, serum PSA, previous negative biopsy, hypoechogenic lesions on TRUS and prostatic volume determined by ultrasonography. All these parameters have independent value in predicting biopsy outcome [7]. On the other hand, to obtain the risk of the PCPT-CRC nomogram, in addition to the former three predictor variables included for the SWOP-PRI, a family history of PCa was also considered. The formula for the latter is:STATISTICAL ANALYSISPredictive variables were compared based on the biopsy outcome, either using a  t -test or chi-squared. Next, an external validation of SWOP-PRI and PCPT-CRC was performed. The predictive accuracy of both tools was assessed by analysis of the area under the receiver–operator characteristic (ROC) curve. The statistical significance of the difference between the areas under the ROC curves was analyzed using the DeLong method [11].All statistical tests were performed with the use of the MedCalc for Windows, version 11.2.1 (MedCalc Software, Mariakerke, Belgium).  P   <  0.05 (two-tailed) was considered statistically significant. RESULTS The characteristics of the study population are shown in Table 1. Among the 390 patients included in the analysis, 121 (31.0%) had history of a previous negative biopsy and 155 (39.7%) were diagnosed with PCa. Age, PSA, DRE, prostate volume and TRUS findings were all significant predictors of PCa.Table 2 displays the rate of PCa detection according to calculated risk for each 1 1 1 79680 8488 0 26930 9054 0 44831 0+ −( )[ ] = − +× ( ) + ×+ × − ×= =( )exp , .. log .. .,PCA beingPCAPSA Familiarhistory DREPrevious biopsy yes no TABLE 1  Characteristics of the patient population submitted to prostate biopsy Variable n Cancer No malignancy P Number of patients (%) 390 (100) 155 (39.7) 235 (60.3)Age (years)Mean  ±   SD 69.2 71.6  ±  8.0 67.6  ±  8.3 < 0.001Range 44–89 44–89 44–87PSA (ng/mL), mean  ±   SD 12.5 17.2  ±  15.75 9.4  ±  7.9 < 0.001Suspicious DRE,  n  (%) 129 (35) 70 (47.0) 59 (26.0) < 0.001Prostate volume (mL)Mean  ±   SD 65.4 52.0  ±  28.6 73.3  ±  33.9 < 0.001Range 15–200 15–192 15–200Hypoechogenic lesion 113 (37%) 53 (48%) 60 (31%) 0.001 Data are also presented according to biopsy outcome. TABLE 2  Rate of prostate cancer detection according to calculated risk for the European Randomized Study of Screening for Prostate Cancer derived Prostate Risk Indicator (SWOP-PRI) and Prostate Cancer Prevention Trial derived Cancer Risk Calculator (PCPT-CRC) nomograms Age (years)Calculated risk (%)SWOP-PRI PCPT-CRC < 15 14.9 14.315–44 31.0 24.045–59 47.8 30.860–74 62.5 45.9 ≥ 75 87.5 76.8 FIG. 1.  Receiver–operator characteristic curves for the European Randomized Study of Screening for Prostate Cancer derived Prostate Risk Indicator (SWOP-PRI) and Prostate Cancer Prevention Trial derived Cancer Risk Calculator (PCPT-CRC).1008060402000 20 40 60100-SpecificitySensitivitySWOP-PRIPCPT-CRC80 100 TABLE 3  Head-to-head comparison of the predictive accuracy of the European Randomized Study of Screening for Prostate Cancer derived Prostate Risk Indicator (SWOP-PRI) and Prostate Cancer Prevention Trial derived Cancer Risk Calculator (PCPT-CRC) nonograms and PSA SWOP-PRI PCPT-CRCPCPT-CRC 0.002 –PSA < 0.001 0.044 O L I V E I R A   E T  A L . ©   2 0 1 0  T H E  A U T H O R S 1 7 8 2 B J U  I N T E R N A T I O N A L   ©  2 0 1 0  B J U  I N T E R N A T I O N A L nomogram. Along with rising SWOP-PRI and PCPT-CRC risks, an increase in the rate of PCa detection is observed.Figure 1 shows the ROC curves for both risk calculators. The accuracy of the SWOP-PRI was 77.9% (95% CI, 0.728–0.823;  P   <  0.001) vs 69.9% (95% CI, 0.645–0.749;  P   <  0.001) for the PCPT-CRC. Comparison of the difference between the areas under the ROC curves using the DeLong method revealed a 7.96% increased predictive accuracy for the SWOP-PRI compared to the PCPT-CRC nomogram in a statistically significant fashion ( P   =  0.002) (Table 3). Moreover, the area under the curve for serum PSA alone was 65.8% (95% CI, 0.602–0.711;  P   <  0.001) and was significantly different from both risk calculators. DISCUSSION PCa risk calculators are valuable tools in the process of prostate biopsy decision-making. By incorporating several predictor variables, these tools have already proved to be superior to PSA alone, particularly in patients presenting several risk factors, and thus should be considered in the office-based clinical practice [6,8].Various predictors of PCa were identified, namely suspicious DRE and TRUS findings and a positive family history [8]. Conversely, increased prostate volume and previous negative biopsy are considered to be negative predictors [2,8].In the present study population, the areas under the curve for the SWOP-PRI and the PCPT-CRC were 77.9% and 69.9%, respectively, thus reproducing the previewed predictive accuracy in the original populations (79.0% and 70.2%, respectively) [1,2]. Moreover, considering the minimal accepted predictive accuracy of nomograms is 70–80% [12], both risk calculators can be considered as adequate.Nonetheless, in the present data set, the SWOP-PRI displays a superior accuracy compared to the PCPT-CRC. According to the results obtained in the present study, and in addition to any geographical and ethnical issues that need to be considered, the information concerning prostate volume and hypoechogenic lesions in ultrasonography appears to confer an added value to the tool when predicting the risk of PCa because these variables are not taken into account in the North-American model.Despite the clinical implementation of these two parameters in all patients often proving difficult, recent data suugest that, even with a relatively approximate estimation of the total prostate volume by DRE, an adaptation of the SWOP-PRI performs better than PSA alone or in combination with DRE [13].Furthermore, previous studies have shown a discrepancy with respect to accuracy according to the population under study, which, as well as for other reasons, could be justified by racial differences [9,10].Both risk calculators were initially developed based on a sextant biopsy regimen, which is no longer current practice. Because the extended biopsy regimens that are now commonly applied will probably decrease the effect of prostate volume on PCa detection, an adaptation of these models is necessary [14]. Moreover, nomograms based on extended biopsy regimens have already shown an increased predictive accuracy compared to previously established models based on 6–10-core biopsies [15].Nonetheless, the obvious limitations of PSA-based tools should be considered when using these nomograms because the inconvenience of PCa over- and under-detection persists [16]. The poor correlation of serum PSA levels with PCa aggressiveness [17] appears to be at least partially responsible for the trend in over-diagnosis and subsequent over-treatment in clinical practice [18]. On the other hand, previous data from the PCPT failed to reveal a PSA threshold with both high sensitivity and specificity when monitoring healthy men [19]. According to that study, to detect more than 80% of PCa cases, the PSA threshold would need to be 1.1 ng/mL, which would mean submitting  > 60% of men without cancer to biopsy. Furthermore, with a threshold of 2.6 ng/mL, only 40% of PCa cases would be detected.Thus, the need for alternative PCa biomarkers has lead research, with the PCA3 test emerging as a strong candidate [20]. Recent data suggest that the use of this marker can decrease the number of unnecessary biopsies and possibly contribute to the reduction of over-diagnosis [21]. Evidence also shows that the PCA3 test may result in a preferential detection of higher risk cancers rather than indolent disease [16]. Additionally, several studies of genetic susceptibility to the development of PCa are also in progress [20].In conclusion, despite their limitations, the risk indicators evaluated in the present study can be of added value when defining a starting point in patient assessment and should be considered in clinical practice. However, improvements regarding the selective identification of men who are susceptible to the development of life-threatening disease are mandatory, and will hopefully contribute to the timely and proper management of these patients. CONFLICT OF INTEREST None declared. REFERENCES 1 Kranse R, Roobol M, Schroder FH.  A graphical device to represent the outcomes of a logistic regression analysis.  Prostate  2008;  68 : 1674–802 Thompson IM, Ankerst DP, Chi C  et al .  Assessing prostate cancer risk: results from the Prostate Cancer Prevention Trial.  J Natl Cancer Inst  2006;  98 : 529–343 Karakiewicz PI, Benayoun S, Kattan MW  et al .  Development and validation of a nomogram predicting the outcome of prostate biopsy based on patient age, digital rectal examination and serum prostate specific antigen.  J Urol  2005;  173 : 1930–44 Garzotto M, Hudson RG, Peters L  et al .  Predictive modeling for the presence of prostate carcinoma using clinical, laboratory, and ultrasound parameters in patients with prostate specific antigen levels  <  or  =  10 ng/mL.  Cancer  2003;  98 : 1417–225 Eastham JA, May R, Robertson JL, Sartor O, Kattan MW.  Development of a nomogram that predicts the probability of a positive prostate biopsy in men with an abnormal digital rectal examination and a prostate-specific antigen between 0 and 4 ng/mL.  Urology  1999;  54 : 709–136 Schroder F, Kattan MW.  The comparability of models for predicting the risk of a positive prostate biopsy with prostate-specific antigen alone: a systematic review.  Eur Urol  2008;  54 : 274–90 O N L I N E  N O M O G R A M S  F O R  P R O S T A T E  B I O P S Y  O U T C O M E ©   2 0 1 0  T H E  A U T H O R SB J U  I N T E R N A T I O N A L   ©  2 0 1 0  B J U  I N T E R N A T I O N A L 1 7 8 3 7 Roobol MJ.  The use of nomograms in the detection of prostate cancer.  Prostate  2006;  66 : 1266–78 Roobol MJ, Schroder FH, Kranse R.  A comparison of first and repeat (four years later) prostate cancer screening in a randomized cohort of a symptomatic men aged 55–75 years using a biopsy indication of 3.0 ng/ml (results of ERSPC, Rotterdam).  Prostate  2006;  66 : 604–129 Utsumi T, Kawamura K, Suzuki H  et al .  External validation and head-to-head comparison of Japanese and Western prostate biopsy nomograms using Japanese data sets.  Int J Urol  2009;  16 : 416–910 Chun FK, Briganti A, Graefen M  et al .  Development and external validation of an extended repeat biopsy nomogram.  J Urol  2007;  177 : 510–511 DeLong ER, DeLong DM, Clarke-Pearson DL.  Comparing the areas under two or more correlated receiver operating characteristic curves: a nonparametric approach.  Biometrics  1988;  44 : 837–4512 Chun FK, Karakiewicz PI, Briganti A  et al .  Prostate cancer nomograms: an update.  Eur Urol  2006;  50 : 914–26; discussion 92613 Roobol MJ, Kranse R, Schröder FH.  Prostate volume adjustment with rectal examination (DRE) within the ERSPC risk calculator.  J Urol  2010;  183 : e714 (AUA Meeting Abstracts Supplement)14 van den Bergh RC, Roobol MJ, Wolters T, van Leeuwen PJ, Schroder FH.  The Prostate Cancer Prevention Trial and European Randomized Study of Screening for Prostate Cancer risk calculators indicating a positive prostate biopsy: a comparison.  BJU Int  2008;  102 : 1068–7315 Kawakami S, Numao N, Okubo Y  et al .  Development, validation, and head-to-head comparison of logistic regression-based nomograms and artificial neural network models predicting prostate cancer on initial extended biopsy.  Eur Urol  2008;  54 : 601–1116 Kirby RS, Fitzpatrick JM, Irani J.  Prostate cancer diagnosis in the new millennium: strengths and weaknesses of prostate-specific antigen and the discovery and clinical evaluation of prostate cancer gene 3 (PCA3).  BJU Int  2009;  103 : 441–517 Fall K, Garmo H, Andren O  et al .  Prostate-specific antigen levels as a predictor of lethal prostate cancer.  J Natl Cancer Inst  2007;  99: 526–3218 Zappa M, Ciatto S, Bonardi R, Mazzotta A. Overdiagnosis of prostate carcinoma by screening: an estimate based on the results of the Florence Screening Pilot Study. Ann Oncol 1998; 9: 1297–30019 Thompson IM, Ankerst DP, Chi C et al. Operating characteristics of prostate-specific antigen in men with an initial PSA level of 3.0 ng/ml or lower. JAMA 2005; 294: 66–7020 Kirby RS, Eeles RA, Kote-Jarai Z, Guy M, Easton D, Fitzpatrick JM. Screening for prostate cancer: the way ahead. BJU Int 2010; 105: 295–721 Haese A, de la Taille A, van Poppel H et al. Clinical utility of the PCA3 urine assay in European men scheduled for repeat biopsy. Eur Urol 2008; 54: 1081–8Correspondence: Mário Oliveira, Department of Urology, Hospital de Braga, Apartado 2242, 4701-965 Braga, Portugal.e-mail: mariooliveira@ecsaude.uminho.ptAbbreviations: PCa, prostate cancer; PCPT-CRC, Prostate Cancer Prevention Trial Cancer Risk Calculator; ROC, receiver–operator characteristic; SWOP-PRI, European Randomized Study of Screening for Prostate Cancer derived Prostate Risk Indicator.

Head-to-head comparison of two online nomograms for prostate biopsy outcome prediction

Repositório Comum

http://comum.rcaap.pt/bitstream/10400.26/4533/1/BJUI.pdf

Head-to-head comparison of two online nomograms for prostate biopsy outcome prediction

Abstract

Similar works

Full text

Available Versions

Institutional repository of Hospital de Braga

Repositório Comum