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Featured researches published by Fritz H. Schröder.


The New England Journal of Medicine | 2009

Screening and Prostate-Cancer Mortality in a Randomized European Study

Fritz H. Schröder; Jonas Hugosson; Monique J. Roobol; Stefano Ciatto; Vera Nelen; Maciej Kwiatkowski; Marcos Lujan; Hans Lilja; Marco Zappa; Louis Denis; Franz Recker; A. Berenguer; Liisa Määttänen; Chris H. Bangma; Gunnar Aus; Arnauld Villers; Xavier Rebillard; Theodorus van der Kwast; Bert G. Blijenberg; Sue Moss; Harry J. de Koning; Anssi Auvinen

BACKGROUND The European Randomized Study of Screening for Prostate Cancer was initiated in the early 1990s to evaluate the effect of screening with prostate-specific-antigen (PSA) testing on death rates from prostate cancer. METHODS We identified 182,000 men between the ages of 50 and 74 years through registries in seven European countries for inclusion in our study. The men were randomly assigned to a group that was offered PSA screening at an average of once every 4 years or to a control group that did not receive such screening. The predefined core age group for this study included 162,243 men between the ages of 55 and 69 years. The primary outcome was the rate of death from prostate cancer. Mortality follow-up was identical for the two study groups and ended on December 31, 2006. RESULTS In the screening group, 82% of men accepted at least one offer of screening. During a median follow-up of 9 years, the cumulative incidence of prostate cancer was 8.2% in the screening group and 4.8% in the control group. The rate ratio for death from prostate cancer in the screening group, as compared with the control group, was 0.80 (95% confidence interval [CI], 0.65 to 0.98; adjusted P=0.04). The absolute risk difference was 0.71 death per 1000 men. This means that 1410 men would need to be screened and 48 additional cases of prostate cancer would need to be treated to prevent one death from prostate cancer. The analysis of men who were actually screened during the first round (excluding subjects with noncompliance) provided a rate ratio for death from prostate cancer of 0.73 (95% CI, 0.56 to 0.90). CONCLUSIONS PSA-based screening reduced the rate of death from prostate cancer by 20% but was associated with a high risk of overdiagnosis. (Current Controlled Trials number, ISRCTN49127736.)


The New England Journal of Medicine | 2012

Prostate-cancer mortality at 11 years of follow-up

Fritz H. Schröder; Jonas Hugosson; Monique J. Roobol; Stefano Ciatto; Vera Nelen; Maciej Kwiatkowski; Marcos Lujan; Hans Lilja; Marco Zappa; Louis Denis; Franz Recker; Alvaro Paez; Liisa Määttänen; Chris H. Bangma; Gunnar Aus; Sigrid Carlsson; Arnauld Villers; Xavier Rebillard; Theodorus van der Kwast; Paula Kujala; Bert G. Blijenberg; Ulf-Håkan Stenman; Andreas Huber; Kimmo Taari; Matti Hakama; Sue Moss; Harry J. de Koning; Anssi Auvinen

BACKGROUND Several trials evaluating the effect of prostate-specific antigen (PSA) testing on prostate-cancer mortality have shown conflicting results. We updated prostate-cancer mortality in the European Randomized Study of Screening for Prostate Cancer with 2 additional years of follow-up. METHODS The study involved 182,160 men between the ages of 50 and 74 years at entry, with a predefined core age group of 162,388 men 55 to 69 years of age. The trial was conducted in eight European countries. Men who were randomly assigned to the screening group were offered PSA-based screening, whereas those in the control group were not offered such screening. The primary outcome was mortality from prostate cancer. RESULTS After a median follow-up of 11 years in the core age group, the relative reduction in the risk of death from prostate cancer in the screening group was 21% (rate ratio, 0.79; 95% confidence interval [CI], 0.68 to 0.91; P=0.001), and 29% after adjustment for noncompliance. The absolute reduction in mortality in the screening group was 0.10 deaths per 1000 person-years or 1.07 deaths per 1000 men who underwent randomization. The rate ratio for death from prostate cancer during follow-up years 10 and 11 was 0.62 (95% CI, 0.45 to 0.85; P=0.003). To prevent one death from prostate cancer at 11 years of follow-up, 1055 men would need to be invited for screening and 37 cancers would need to be detected. There was no significant between-group difference in all-cause mortality. CONCLUSIONS Analyses after 2 additional years of follow-up consolidated our previous finding that PSA-based screening significantly reduced mortality from prostate cancer but did not affect all-cause mortality. (Current Controlled Trials number, ISRCTN49127736.).


The Lancet | 2000

Maximum androgen blockade in advanced prostate cancer: an overview of the randomised trials

O. Dalesio; H. Van Tinteren; M Clarke; R. Peto; Fritz H. Schröder; I Dechering; V Evans; J Godwin; B A Blumenstein; Crawford; L. Denis; R Hall; C Hill; P Iversen; W U Shipley; M. Soloway; R Sylvester; Collaborat Pct.

BACKGROUND In advanced prostate cancer, androgen suppression (AS) by surgery or drugs controls testicular hormone secretion, and the further addition of an antiandrogen such as nilutamide, flutamide, or cyproterone acetate is referred to as maximum androgen blockade (MAB). The aim of this overview was to compare the effects on the duration of survival of MAB and of AS alone. METHODS The collaborative meta-analysis of 27 randomised trials involved central reanalysis of the data on each of 8275 men (98% of those ever randomised in trials of MAB vs AS) with metastatic (88%) or locally advanced (12%) prostate cancer. Half were over 70 years of age, and follow-up was typically for about 5 years. FINDINGS 5932 (72%) men have died; of the deaths for which causes were provided, about 80% were attributed to prostate cancer. 5-year survival was 25.4% with MAB versus 23.6% with AS alone, a non-significant gain of 1.8% (SE 1.3; logrank 2p=0.11). There was no significant heterogeneity in the treatment effect (MAB vs AS) with respect to age or disease stage. The results for cyproterone acetate, which accounted for only a fifth of the evidence, appeared slightly unfavourable to MAB (5-year survival 15.4% MAB vs 18.1% AS alone; difference -2.8% [SE 2.4]; logrank 2p=0.04 adverse), whereas those for nilutamide and flutamide appeared slightly favourable (5-year survival 27.6% MAB vs 24.7% AS alone; difference 2.9% [SE 1.3]; logrank 2p=0.005). Non-prostate-cancer deaths (although not clearly significantly affected by treatment) accounted for some of the apparently adverse effects of cyproterone acetate. INTERPRETATION In advanced prostate cancer, addition of an antiandrogen to AS improved the 5-year survival by about 2% or 3% (depending on whether the analysis includes or excludes the cyproterone acetate trials), but the range of uncertainty as to the true size of this benefit runs from about 0% to about 5%.


BJUI | 2008

The efficacy and safety of degarelix: a 12-month, comparative, randomized, open-label, parallel-group phase III study in patients with prostate cancer

Laurence Klotz; Laurent Boccon-Gibod; Neal D. Shore; Cal Andreou; Bo-Eric Persson; Per Cantor; Jens-Kristian Jensen; Tine Kold Olesen; Fritz H. Schröder

To evaluate the efficacy and safety of degarelix, a new gonadotrophin‐releasing hormone (GnRH) antagonist (blocker), vs leuprolide for achieving and maintaining testosterone suppression in a 1‐year phase III trial involving patients with prostate cancer.


European Urology | 2013

Active Surveillance for Low-Risk Prostate Cancer Worldwide: The PRIAS Study

Meelan Bul; Xiaoye Zhu; Riccardo Valdagni; Tom Pickles; Yoshiyuki Kakehi; Antti Rannikko; Anders Bjartell; Deric K. van der Schoot; Erik B. Cornel; Giario Conti; Egbert R. Boevé; Frédéric Staerman; Jenneke J. Vis-Maters; Henk Vergunst; Joris J. Jaspars; Petra Strölin; Erik van Muilekom; Fritz H. Schröder; Chris H. Bangma; Monique J. Roobol

BACKGROUND Overdiagnosis and subsequent overtreatment are important side effects of screening for, and early detection of, prostate cancer (PCa). Active surveillance (AS) is of growing interest as an alternative to radical treatment of low-risk PCa. OBJECTIVE To update our experience in the largest worldwide prospective AS cohort. DESIGN, SETTING, AND PARTICIPANTS Eligible patients had clinical stage T1/T2 PCa, prostate-specific antigen (PSA) ≤ 10 ng/ml, PSA density <0.2 ng/ml per milliliter, one or two positive biopsy cores, and Gleason score ≤ 6. PSA was measured every 3-6 mo, and volume-based repeat biopsies were scheduled after 1, 4, and 7 yr. Reclassification was defined as more than two positive cores or Gleason >6 at repeat biopsy. Recommendation for treatment was triggered in case of PSA doubling time <3 yr or reclassification. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS Multivariate regression analysis was used to evaluate predictors for reclassification at repeat biopsy. Active therapy-free survival (ATFS) was assessed with a Kaplan-Meier analysis, and Cox regression was used to evaluate the association of clinical characteristics with active therapy over time. RESULTS AND LIMITATIONS In total, 2494 patients were included and followed for a median of 1.6 yr. One or more repeat biopsies were performed in 1480 men, of whom 415 men (28%) showed reclassification. Compliance with the first repeat biopsy was estimated to be 81%. During follow-up, 527 patients (21.1%) underwent active therapy. ATFS at 2 yr was 77.3%. The strongest predictors for reclassification and switching to deferred treatment were the number of positive cores (two cores compared with one core) and PSA density. The disease-specific survival rate was 100%. Follow-up was too short to draw definitive conclusions about the safety of AS. CONCLUSIONS Our short-term data support AS as a feasible strategy to reduce overtreatment. Clinical characteristics and PSA kinetics during follow-up can be used for risk stratification. Strict monitoring is even more essential in men with high-risk features to enable timely recognition of potentially aggressive disease and offer curative intervention. Limitations of using surrogate end points and markers in AS should be recognized. TRIAL REGISTRATION The current program is registered at the Dutch Trial Register with ID NTR1718 (http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=1718).


The Journal of Urology | 1993

A Prospective European Organization for Research and Treatment of Cancer Genitourinary Group Randomized Trial Comparing Transurethral Resection Followed by a Single Intravesical Instillation of Epirubicin or Water in Single Stage Ta, T1 Papillary Carcinoma of the Bladder

Willem Oosterlinck; Karl Heinz Kurth; Fritz H. Schröder; Jozef Bultinck; Bernadette Hammond; Richard Sylvester

A total of 431 eligible patients with solitary, primary or recurrent stages Ta and T1 transitional cell carcinoma of the bladder was included in a randomized multicenter trial to compare a single intravesical instillation of 80 mg. epirubicin with water given immediately after resection, with respect to the disease-free interval and recurrence rate. The interval to initial recurrence was significantly better in favor of the epirubicin group. After a mean followup of 2 years it became evident that the recurrence rate after a single epirubicin instillation was decreased by nearly half with the same trend being found in all subgroups examined. Toxicity was mainly restricted to bladder irritation in plus or minus 10% of the cases. Pathology review brought considerable changes in T category from stages T1 to Ta (53%). Changes in grade were less pronounced but nevertheless important.


European Urology | 2014

Prospective Study of Diagnostic Accuracy Comparing Prostate Cancer Detection by Transrectal Ultrasound–Guided Biopsy Versus Magnetic Resonance (MR) Imaging with Subsequent MR-guided Biopsy in Men Without Previous Prostate Biopsies

Morgan Pokorny; Maarten de Rooij; Earl Duncan; Fritz H. Schröder; Robert Parkinson; Jelle O. Barentsz; Leslie Thompson

BACKGROUND The current diagnosis of prostate cancer (PCa) uses transrectal ultrasound-guided biopsy (TRUSGB). TRUSGB leads to sampling errors causing delayed diagnosis, overdetection of indolent PCa, and misclassification. Advances in multiparametric magnetic resonance imaging (mpMRI) suggest that imaging and selective magnetic resonance (MR)-guided biopsy (MRGB) may be superior to TRUSGB. OBJECTIVE To compare the diagnostic efficacy of the magnetic resonance imaging (MRI) pathway with TRUSGB. DESIGN, SETTING, AND PARTICIPANTS A total of 223 consecutive biopsy-naive men referred to a urologist with elevated prostate-specific antigen participated in a single-institution, prospective, investigator-blinded, diagnostic study from July 2012 through January 2013. INTERVENTION All participants had mpMRI and TRUSGB. Men with equivocal or suspicious lesions on mpMRI also underwent MRGB. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS The primary outcome was PCa detection. Secondary outcomes were histopathologic details of biopsy and radical prostatectomy specimens, adverse events, and MRI reader performance. Sensitivity, specificity, negative predictive values (NPVs), and positive predictive values were estimated and basic statistics presented by number (percentage) or median (interquartile range). RESULTS AND LIMITATIONS Of 223 men, 142 (63.7%) had PCa. TRUSGB detected 126 cases of PCa in 223 men (56.5%) including 47 (37.3%) classed as low risk. MRGB detected 99 cases of PCa in 142 men (69.7%) with equivocal or suspicious mpMRI, of which 6 (6.1%) were low risk. The MRGB pathway reduced the need for biopsy by 51%, decreased the diagnosis of low-risk PCa by 89.4%, and increased the detection of intermediate/high-risk PCa by 17.7%. The estimated NPVs of TRUSGB and MRGB for intermediate/high-risk disease were 71.9% and 96.9%, respectively. The main limitation is the lack of long follow-up. CONCLUSIONS We found that mpMRI/MRGB reduces the detection of low-risk PCa and reduces the number of men requiring biopsy while improving the overall rate of detection of intermediate/high-risk PCa. PATIENT SUMMARY We compared the results of standard prostate biopsies with a magnetic resonance (MR) image-based targeted biopsy diagnostic pathway in men with elevated prostate-specific antigen. Our results suggest patient benefits of the MR pathway. Follow-up of negative investigations is required.


International Journal of Cancer | 2002

Large-scale randomized prostate cancer screening trials: Program performances in the European randomized screening for prostate cancer trial and the prostate, lung, colorectal and ovary cancer trial

Harry J. de Koning; Anssi Auvinen; Antonio Berenguer Sanchez; Fernando Calais da Silva; Stefano Ciatto; Louis Denis; John K. Gohagan; Matti Hakama; Jonas Hugosson; Ries Kranse; Vera Nelen; Philip C. Prorok; Fritz H. Schröder

Two large‐scale randomized screening trials, the Prostate, Lung, Colorectal and Ovary (PLCO) cancer trial in the USA and the European Randomized Screening for Prostate Cancer (ERSPC) trial in Europe are currently under way, aimed at assessing whether screening reduces prostate cancer mortality. Up to the end of 1998, 102,691 men have been randomized to the intervention arm and 115,322 to the control arm (which represents 83% of the target sample size) from 7 European countries and 10 screening centers in the USA. The principal screening method at all centers is determination of serum prostate‐specific antigen (PSA). The PLCO trial and some European centers use also digital rectal examination (DRE) as an ancillary screening test. In the core age group (55–69 years), 3,362 of 32,486 men screened (10%) had a serum PSA concentration of 4 ng/ml or greater, which is 1 cut‐off for biopsy (performed in 84%). An additional 6% was referred for further assessment based on other criteria, with much less efficiency. Differences in PSA by country are largely attributable to the age structure of the study population. The mean age‐specific PSA levels are lower in the PLCO trial (1.64 ng/ml [in the age group 55–59 years], 1.80 [60–64 years] and 2.18 [65–69 years) than in the ERSPC trial (1.28–1.71 [55–59], 1.75–2.87 [60–64] and 2.48–3.06 [65–69 years]). Detection rates at the first screen in the ERSPC trial range from 11 to 42/1,000 men screened and reflect underlying differences in incidence rates and screening procedures. In centers with consent to randomization design, adherence in the screening arm is 91%, but less than half of the men in the target population are enrolled in the trial. In population‐based centers in which men were randomized prior to consent, all eligible subjects are enrolled, but only about two‐thirds of the men in the intervention arm undergo screening. Considerable progress has been made in both trials. Enrollment will be completed in 2001. A substantial number of early prostate cancers have been detected. The differences between countries seem to reflect both underlying prostate cancer incidence and screening policy. The trials have the power to show definitive results in 2005–2008.


Journal of Clinical Oncology | 2007

Identification of Patients With Prostate Cancer Who Benefit From Immediate Postoperative Radiotherapy: EORTC 22911

Theodorus van der Kwast; Michel Bolla; Hendrik Van Poppel; Paul Van Cangh; K. Vekemans; Luigi Da Pozzo; Jean-François Bosset; Karl Heinz Kurth; Fritz H. Schröder; Laurence Collette

PURPOSE The randomized controlled European Organisation for Research and Treatment of Cancer (EORTC) trial 22911 studied the effect of radiotherapy after prostatectomy in patients with adverse risk factors. Review pathology data of specimens from participants in this trial were analyzed to identify which factors predict increased benefit from adjuvant radiotherapy. PATIENTS AND METHODS After prostatectomy, 1,005 patients with stage pT3 and/or positive surgical margins were randomly assigned to a wait-and-see (n = 503) and an adjuvant radiotherapy (60 Gy conventional irradiation) arm (n = 502). Pathologic review data were available for 552 patients from 11 participating centers. The interaction between the review pathology characteristics and treatment benefit was assessed by log-rank test for heterogeneity (P < .05). RESULTS Margin status assessed by review pathology was the strongest predictor of prolonged biochemical disease-free survival with immediate postoperative radiotherapy (heterogeneity, P < .01): by year 5, immediate postoperative irradiation could prevent 291 events/1,000 patients with positive margins versus 88 events/1,000 patients with negative margins. The hazard ratio for immediate irradiation was 0.38 (95% CI, 0.26 to 0.54) and 0.88 (95% CI, 0.53 to 1.46) in the groups with positive and negative margins, respectively. We could not identify a significant impact of the positive margin localization. CONCLUSION Provided careful pathology of the prostatectomy is performed, our results suggest that immediate postoperative radiotherapy might not be recommended for prostate cancer patients with negative surgical margins. These findings require validation on an independent data set.


Annals of Internal Medicine | 2008

Insulin-like Growth Factors, Their Binding Proteins, and Prostate Cancer Risk: Analysis of Individual Patient Data from 12 Prospective Studies

Andrew W. Roddam; Naomi E. Allen; Paul N. Appleby; Timothy J. Key; Luigi Ferrucci; H. Ballentine Carter; E. Jeffrey Metter; Chu Chen; Noel S. Weiss; Annette L. Fitzpatrick; Ann W. Hsing; James V. Lacey; Kathy J. Helzlsouer; Sabina Rinaldi; Elio Riboli; Rudolf Kaaks; Joop A. M. J. L. Janssen; Mark F. Wildhagen; Fritz H. Schröder; Elizabeth A. Platz; Michael Pollak; Edward Giovannucci; Catherine Schaefer; Charles P. Quesenberry; Joseph H. Vogelman; Gianluca Severi; Dallas R. English; Graham G. Giles; Pär Stattin; Göran Hallmans

Context Insulin-like growth factors (IGFs) and IGF binding proteins may be associated with some cancers. Contribution This reanalysis of individual patient data from 12 studies of the association between IGFs and IGF binding proteins and prostate cancer suggests that higher levels of serum IGF-I are associated with higher risk for prostate cancer. Caution The 12 studies varied in the types of patients they studied and in how they measured IGFs. Implication High IGF-I levels seem to be a risk factor for prostate cancer. The Editors Prostate cancer is one of the most common types of cancer in men, yet few risk factors for the disease, other than age, race, and a family history, have been established (1, 2). Insulin-like growth factors (IGFs) and their associated binding proteins (IGFBPs) have been the subject of many epidemiologic investigations of prostate cancer because they are known to help regulate cell proliferation, differentiation, and apoptosis (3). Although results from some, but not all, studies suggest an association between IGFs and IGFBPs and prostate cancer risk, there has been much uncertainty about its consistency and magnitude. A previous meta-analysis that included only 3 prospective studies suggested that high levels could be associated with more than a 2-fold increase in risk (4), although recent studies have suggested the risk is lower. Furthermore, given that these peptides are correlated with each other, uncertainty remains about any observed relationships. The individual studies are rarely large enough to allow proper mutual adjustment for these correlated factors, and they are insufficiently powered to investigate the consistency of their findings in key subgroups (for example, stage and grade of disease). Such analyses are important because studies have suggested that IGF-I might be more associated with advanced than with localized disease (5, 6). The Endogenous Hormones and Prostate Cancer Collaborative Group was established to conduct collaborative reanalyses of individual data from prospective studies on the relationships between circulating levels of sex hormones and IGFs and subsequent prostate cancer risk. Results for the sex hormones have been reported elsewhere and show no statistically significant relation between androgen or estrogen levels in men and the subsequent risk for prostate cancer (7). We report results for concentrations of IGFs and IGFBPs. Methods Participants The Endogenous Hormones and Prostate Cancer Collaborative Group is described in detail elsewhere (7). In brief, the group invited principal investigators of all studies, found by searching PubMed, Web of Science, and CancerLit, that provided data on circulating concentrations of sex steroids, IGFs or IGFBPs, and prostate cancer risk by using prospectively collected blood samples to join the collaboration. Thirteen studies collected data on circulating IGF concentrations and the subsequent risk for prostate cancer (5, 6, 820), of which 1 contributed only data on sex hormones (20). Eleven of the studies used a matched casecontrol design nested within a prospective cohort study (5, 6, 812, 16, 19) or a randomized trial (1315, 17). One study used a casecohort design (18) and was converted into a matched casecontrol design by randomly matching up to 3 control participants to each case patient by age at recruitment, time between blood collection and diagnosis, time of blood draw, and race. (Table 1 provides a full description of the studies and matching criteria used.) Most of the prospective studies were population-based, with the exception of 1 based on health plan members (9), 1 that recruited male health professionals (16), and 1 that was a combination of an intervention study and a monitoring study for cardiovascular disease (6, 10). Two of the randomized trials did not have prostate cancer as a primary end point (5, 8, 15); the other 2 were based within a screening trial (13) or were about treatment of prostate-specific antigen (PSA)detected prostate cancer (14). Table 1. Study Characteristics Individual participant data were available for age; height; weight; smoking status; alcohol consumption; marital status; socioeconomic status (assessed by educational achievement); race; concentrations of IGFs, IGFBPs, and endogenous sex steroids; and PSA level. Information sought about prostate cancer included date of diagnosis, stage and grade of disease, and method of case patient ascertainment. Some studies (5, 6, 8, 10, 16) published more than 1 article or performed assays at different times on the association between IGFs and prostate cancer risk, sometimes with different matched casecontrol sets, laboratory measurements, and durations of follow-up. For each study, we created a single data set in which each participant appeared only once. In our analysis, we treated any participant who appeared in a study as both a control participant and a case patient as a case patient only. We removed matched set identifiers, and we generated a series of strata (equivalent to matched sets) in which participants in each study were grouped according to age at recruitment (2-year age bands) and date of recruitment (by year), because these matching criteria were common to most studies (Table 1). The number of strata used in the collaborative analysis was slightly less than that of matched sets used in the original analyses. To ensure that this process did not introduce any bias, we checked that the results for each study, using the original matched sets, were the same as those using the strata described above. Tumors were classified as advanced if the tumor was described as extending beyond the prostate capsule (T3/T4), and/or there was lymph node involvement (N1/N2/N3), and/or there were distant metastases (M1); tumors were classified as localized if they were T0/T1/T2 and N0/NX and M0. We classified tumors as high-grade if they had a Gleason score of 7 or more or were moderately poorly or poorly differentiated; otherwise, they were classified as low-grade. Statistical Analysis We calculated partial correlation coefficients between log-transformed IGF and IGFBP concentrations among control participants, adjusted for age at blood collection (<50, 50 to 59, 60 to 69, or 70 years) and study. For each IGF and IGFBP, we categorized men into quintiles of IGF and IGFBP serum concentrations, with cut-points defined by the study-specific quintiles of the distribution within control participants. For studies with more than 1 publication or in which the serum assays were done at different times, resulting in different absolute levels of IGFs (5, 6, 8, 10, 16), we calculated cut-points separately for each substudy. We used a conditional logistic regression stratified by study, age at recruitment (2-year age bands), and date of recruitment (single year) as our main method of analysis. To provide a summary measure of risk, we calculated a linear trend by scoring the quintiles of the serum IGF or IGFBP concentrations as 0, 0.25, 0.5, 0.75, and 1. Under the assumption of linearity, a unit change in this trend variable is equivalent to the odds ratio (OR) comparing the highest with the lowest quintile. All results are unadjusted for participant characteristics, except for those controlled by the stratification variables. We examined the possible influence of 5 participant characteristics by adjusting the relevant conditional logistic regression models for body mass index (BMI) (<22.5, 22.5 to 24.9, 25.0 to 27.4, 27.5 to 29.9, or >30 kg/m2), marital status (married or cohabiting, or not married or cohabiting), educational status (did not attend college or university, or attended college or university), smoking (never, previous, or current), and alcohol consumption (<10 or 10 g/d). We excluded participants from the analysis if they had a missing value for the characteristic under examination. We assessed heterogeneity in linear trends among studies by using a chi-square statistic to test whether the study-specific ORs were statistically different from the overall OR (21). Heterogeneity among studies was also quantified by calculating the H and I 2 statistics (22). To test whether the linear trend OR estimates for each IGF and IGFBP varied according to case patient characteristics, we estimated a series of subsets for each characteristic: stage at diagnosis (localized or advanced), grade at diagnosis (low or high), year of diagnosis (before 1990, 1990 to 1994, or 1995 onward; these year cutoffs were chosen to attempt to reflect differences in the use of the PSA test for cancer detection), age at diagnosis (<60, 60 to 69, or 70 years), and time between blood collection and diagnosis (<3, 3 to 6, or 7 years). We excluded case patients from the analyses of stage and grade at diagnosis if the relevant information was not available. For each of these case patient characteristics, we calculated a heterogeneity chi-square statistic to assess whether the estimated ORs statistically differed from each other (21). To assess whether the OR estimate of the linear trend for each IGF or IGFBP varied according to PSA level at recruitment (<2 g/L or 2 g/L), we entered an interaction term into the conditional logistic regression model for each IGF or IGFBP, and we tested the statistical significance of the interaction term with a likelihood ratio test. Statistical significance was set at the 5% level. All statistical tests were 2-sided. All statistical analyses were done with Stata, version 9.0 (StataCorp, College Station, Texas). Results Table 1 shows the characteristics of the studies. The 12 prospective studies included approximately 3700 case patients with prostate cancer and 5200 control participants. Insulin-like growth factor I and IGFBP-III measurements were available for all and 3600 case patients, respectively. However, IGF-II and IGFBP-II measurements were available for only 379 and 419 case patients, respectively (Table 2). Mean age at blood collection

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Monique J. Roobol

Erasmus University Medical Center

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Chris H. Bangma

Erasmus University Rotterdam

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Ries Kranse

Erasmus University Rotterdam

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Jonas Hugosson

Sahlgrenska University Hospital

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Tineke Wolters

Erasmus University Rotterdam

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Pim J. van Leeuwen

Erasmus University Rotterdam

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Harry J. de Koning

Erasmus University Rotterdam

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Stijn Roemeling

Erasmus University Rotterdam

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