A different method of evaluation of the ERSPC trial confirms that prostate-specific antigen testing has a significant impact on prostate cancer mortality

Development and validation of an imageless machine-learning algorithm for the initial screening of prostate cancer

PURPOSE

Prostate specific antigen (PSA) testing is a low-cost screening method for prostate cancer (PCa). However, its accuracy is limited. While progress is being made using medical imaging for PCa screening, PSA testing can still be improved as an easily accessible first step in the screening process. We aimed to develop and validate a new model by further personalizing the analysis of PSA with demographic, medical history, lifestyle parameters, and digital rectal examination (DRE) results.

METHODS

Using data from 34,224 patients in the screening arm of the PLCO trial (22,188 for the training set and 12,036 for the validation set), we applied a gradient-boosting model whose features (Model 1) were one PSA value and the personal variables available in the PLCO trial except those that signaled an ex-ante assumption of PCa. A second algorithm (Model 2) included a DRE result. The primary outcome was the occurrence of PCa, while the aggressiveness of PCa was a secondary outcome. ROC analyses were used to compare both models to other initial screening tests.

RESULTS

The areas under the curve (AUC) for Model 2 was 0.894 overall and 0.908 for patients with a suspicious DRE, compared to 0.808 for PSA for patients with a suspicious DRE. The AUC for Model 1 was 0.814 compared to 0.821 for PSA. Model 2 predicted 58% more high-risk PCa than PSA ≥4 combined with an abnormal DRE and had a positive predictive value of 74.7% (vs. 50.6%).

CONCLUSION

Personalizing the interpretation of PSA values and DRE results with a gradient-boosting model showed promising results as a potential novel, low-cost method for the initial screening of PCa. The importance of DRE, when included in such a model, was also highlighted.

Intervention-related Deaths in the European Randomized Study of Screening for Prostate Cancer

Background

Identification of intervention-related deaths is important for an accurate assessment of the ratio of benefit to harm in screening trials.

Objective

To investigate intervention-related deaths by study arm in the European Randomized Study of Prostate Cancer Screening (ERSPC).

Design, setting, and participants

ERSPC is a multicenter trial initiated in the 1990s to investigate whether screening on the basis of prostate-specific antigen (PSA) can decrease prostate cancer mortality. The present study included men in the core age group (55–69 yr: screening group n = 112 553, control group n = 128 681) with 16-yr follow-up.

Outcome measurements and statistical analysis

Causes of death among men with prostate cancer in ERSPC were predominantly evaluated by independent national committees via review of medical records according to a predefined algorithm. Intervention-related deaths were defined as deaths caused by complications during the screening procedure, treatment, or follow-up. Descriptive statistics were used for the results.

Results and limitations

In total, 34 deaths were determined to be intervention-related, of which 21 were in the screening arm and 13 in the control arm. The overall risk of intervention-related death was 1.41 (95% confidence interval 0.99–1.99) per 10 000 randomized men for both arms combined and varied among centers from 0 to 7.0 per 10 000 randomized men. A limitation of this study is that differences in procedures among centers decreased the comparability of the results.

Conclusions

Intervention-related deaths were rare in ERSPC. Monitoring of intervention-related deaths in screening trials is important for assessment of harms.

Patient summary

We investigated deaths due to screening or treatment to assess harm in a trial of prostate cancer screening. Few such deaths were identified.

Metastatic Prostate Cancer Incidence and Prostate-specific Antigen Testing: New Insights from the European Randomized Study of Screening for Prostate Cancer

BACKGROUND

The European Randomized Study of Screening for Prostate Cancer (ERSPC) has shown a 21% reduction in prostate cancer (PCa) mortality and a 1.6-fold increase in PCa incidence with prostate-specific antigen (PSA)-based screening (at 13 yr of follow-up). We evaluated PCa incidence by risk category at diagnosis across the study arms to assess the potential impact on PCa mortality.

DESIGN, SETTING, AND PARTICIPANTS

Information on arm, centre, T and M stage, Gleason score, serum PSA at diagnosis, age at randomisation, follow-up time, and vital status were extracted from the ERSPC database. Four risk categories at diagnosis were defined: 1, low; 2, intermediate; 3, high; 4, metastatic disease. PSA (≤100 or >100 ng/ml) was used as the indicator of metastasis.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Incidence rate ratios (IRRs) for screening versus control arm by risk category at diagnosis and follow-up time were calculated using Poisson regression analysis for seven centres. Follow-up was truncated at 13 yr. Missing data were imputed using chained equations. The analyses were carried out on an intention-to-treat basis.

RESULTS AND LIMITATIONS

In the screening arm, 7408 PCa cases were diagnosed and 6107 in the control arm. The proportion of missing stage, Gleason score, or PSA value was comparable in the two arms (8% vs 10%), but differed among centres. The IRRs were elevated in the screening arm for the low-risk (IRR: 2.14; 95% CI, 2.03-2.25) and intermediate-risk (IRR: 1.24; 95% CI, 1.16-1.34) categories at diagnosis, equal to unity for the high-risk category at diagnosis (IRR: 1.00; 95% CI, 0.89-1.13), and reduced for metastatic disease at diagnosis (IRR: 0.60; 95% CI, 0.52-0.70). The IRR of metastatic disease had temporal pattern similar to mortality, shifted forwards an average of almost 3 yr, although the mortality reduction was smaller.

CONCLUSIONS

The results confirm a reduction in metastatic disease at diagnosis in the screening arm, preceding mortality reduction by almost 3 yr.

PATIENT SUMMARY

The findings of this study indicate that the decrease in metastatic disease at diagnosis is the major determinant of the prostate cancer mortality reduction in the European Randomized study of Screening for Prostate Cancer.

Impact of Early Diagnosis of Prostate Cancer on Survival Outcomes

CONTEXT

The relationship between early detection of prostate cancer (PCa) and disease-specific mortality is still the subject of much debate.

OBJECTIVE

This review describes developments in PCa mortality rates and disease-stage shift on a population level. The main findings from the randomised screening trials are also discussed. Finally, we consider the expected consequences for the individual man interested in screening.

EVIDENCE ACQUISITION

The PubMed database was searched for trials of screening for PCa from inception through October 11, 2014. Supplementary information was collected by cross-referencing the reference lists.

EVIDENCE SYNTHESIS

Since the introduction of prostate-specific antigen testing, PCa incidence has risen, and a stage shift towards more favourable disease at diagnosis has been observed. PCa mortality rates are gradually decreasing. Although screening trials show conflicting results, the largest randomised trial of screening for PCa shows a 21% decrease in PCa-specific mortality. After correction for noncompliance and contamination, a risk reduction in PCa-specific mortality of up to 49% has been reported. The main side effect of screening is that some studies have estimated that approximately 50% of detected cases may represent overdiagnosis, which may be reduced by stopping screening in older men and using an individual risk-based approach.

CONCLUSIONS

To maximise the benefits while minimising the risk of overdiagnosis, future screening should follow an individual risk-based approach.

PATIENT SUMMARY

On a population level, the introduction of screening for prostate cancer (PCa) is associated with more men diagnosed but with more favourable disease. The largest screening study confirmed the reduction in death due to PCa. Individual risk estimation is important to best balance the benefits and potential harms of early detection.

Do Treatment Differences between Arms Affect the Main Outcome of ERSPC Rotterdam?

PURPOSE

We assessed differences in treatment between the screening and control arms of ERSPC Rotterdam and studied whether possible treatment differences could explain the positive study outcome.

MATERIALS AND METHODS

In ERSPC Rotterdam men 55 to 74 years old were randomized to a screening arm of 21,210 and a control arm of 21,166. Treatment after diagnosis was at the discretion of the care provider chosen by the patient. Initial treatment was compared in 4 risk groups. The relation between prostate cancer incidence and prostate cancer mortality was assessed by risk group by correlating the incidence RR and the mortality RR. A direct relation would have supported a stage shift as the main cause of changes in prostate cancer mortality.

RESULTS

Initial treatment differed between the arms in the low, intermediate and high risk groups but not in the metastatic group. The RRs of prostate cancer incidence and mortality per risk group were related 1:1 (regression line slope 1.00, 95% CI 0.30-1.74). Of changes in prostate cancer mortality 94% could be explained by changes in prostate cancer incidence. This made treatment differences unlikely as the reason for the observed decrease in prostate cancer mortality.

CONCLUSIONS

Differences in treatment between the ERSPC Rotterdam screening and control arms were unlikely to explain the differences in prostate cancer mortality. Results are instead consistent with a decrease in prostate cancer mortality as the result of a favorable stage through screening.

Screening and prostate cancer mortality: results of the European Randomised Study of Screening for Prostate Cancer (ERSPC) at 13 years of follow-up

BACKGROUND

The European Randomised study of Screening for Prostate Cancer (ERSPC) has shown significant reductions in prostate cancer mortality after 9 years and 11 years of follow-up, but screening is controversial because of adverse events such as overdiagnosis. We provide updated results of mortality from prostate cancer with follow-up to 2010, with analyses truncated at 9, 11, and 13 years.

METHODS

ERSPC is a multicentre, randomised trial with a predefined centralised database, analysis plan, and core age group (55-69 years), which assesses prostate-specific antigen (PSA) testing in eight European countries. Eligible men aged 50-74 years were identified from population registries and randomly assigned by computer generated random numbers to screening or no intervention (control). Investigators were masked to group allocation. The primary outcome was prostate cancer mortality in the core age group. Analysis was by intention to treat. We did a secondary analysis that corrected for selection bias due to non-participation. Only incidence and no mortality data at 9 years' follow-up are reported for the French centres. This study is registered with Current Controlled Trials, number ISRCTN49127736.

FINDINGS

With data truncated at 13 years of follow-up, 7408 prostate cancer cases were diagnosed in the intervention group and 6107 cases in the control group. The rate ratio of prostate cancer incidence between the intervention and control groups was 1·91 (95% CI 1·83-1·99) after 9 years (1·64 [1·58-1·69] including France), 1·66 (1·60-1·73) after 11 years, and 1·57 (1·51-1·62) after 13 years. The rate ratio of prostate cancer mortality was 0·85 (0·70-1·03) after 9 years, 0·78 (0·66-0·91) after 11 years, and 0·79 (0·69-0·91) at 13 years. The absolute risk reduction of death from prostate cancer at 13 years was 0·11 per 1000 person-years or 1·28 per 1000 men randomised, which is equivalent to one prostate cancer death averted per 781 (95% CI 490-1929) men invited for screening or one per 27 (17-66) additional prostate cancer detected. After adjustment for non-participation, the rate ratio of prostate cancer mortality in men screened was 0·73 (95% CI 0·61-0·88).

INTERPRETATION

In this update the ERSPC confirms a substantial reduction in prostate cancer mortality attributable to testing of PSA, with a substantially increased absolute effect at 13 years compared with findings after 9 and 11 years. Despite our findings, further quantification of harms and their reduction are still considered a prerequisite for the introduction of populated-based screening.

FUNDING

Each centre had its own funding responsibility.

Characterization and evaluation of DOTA-conjugated Bombesin/RGD-antagonists for prostate cancer tumor imaging and therapy

INTRODUCTION

Here we present the metallation, characterization, in vivo and in vitro evaluations of dual-targeting, peptide-based radiopharmaceuticals with utility for imaging and potentially treating prostate tumors by virtue of their ability to target the αVβ3 integrin or the gastrin releasing peptide receptor (GRPr).

METHODS

[RGD-Glu-6Ahx-RM2] (RGD: Arg-Gly-Asp; Glu: glutamic acid; 6-Ahx: 6-amino hexanoic acid; RM2: (D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2)) was conjugated to a DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) bifunctional chelator (BFCA) purified via reversed-phase high-performance liquid chromatography (RP-HPLC), characterized by electrospray ionization-mass spectrometry (ESI-MS), and radiolabeled with (111)In or (177)Lu. Natural-metallated compounds were assessed for binding affinity for the αVβ3 integrin or GRPr in human glioblastoma U87-MG and prostate PC-3 cell lines and stability prior to in vivo evaluation in normal CF-1 mice and SCID mice xenografted with PC-3 cells.

RESULTS

Competitive displacement binding assays with PC-3 and U87-MG cells revealed high to moderate binding affinity for the GRPr or the αVβ3 integrin (IC50 range of 5.39±1.37 nM to 9.26±0.00 nM in PC-3 cells, and a range of 255±47 nM to 321±85 nM in U87-MG cells). Biodistribution studies indicated high tumor uptake in PC-3 tumor-bearing mice (average of 7.40±0.53% ID/g at 1h post-intravenous injection) and prolonged retention of tracer (mean of 4.41±0.91% ID/g at 24h post-intravenous injection). Blocking assays corroborated the specificity of radioconjugates for each target. Micro-single photon emission computed tomography (microSPECT) confirmed favorable radiouptake profiles in xenografted mice at 20h post-injection.

CONCLUSIONS

[RGD-Glu-[(111)In-DO3A]-6-Ahx-RM2] and [RGD-Glu-[(177)Lu- DO3A]-6-Ahx-RM2] show favorable pharmacokinetic and radiouptake profiles, meriting continued evaluation for molecular imaging in murine U87-MG/PC-3 xenograft models and radiotherapy studies with (177)Lu and (90)Y conjugates.

ADVANCES IN KNOWLEDGE AND IMPLICATIONS FOR PATIENT CARE

These heterovalent, peptide-targeting ligands perform comparably with many mono- and multivalent conjugates with the potential benefit of increased sensitivity for detecting cancer cells exhibiting differential expression of target receptors.

Correlation and diagnostic performance of the prostate-specific antigen level with the diagnosis, aggressiveness, and bone metastasis of prostate cancer in clinical practice

Purpose

The common tool for diagnosing prostate cancer is serum prostate-specific antigen (PSA) testing and digital rectal examination, but the disadvantage of the high sensitivity and low specificity of PSA testing in the diagnosis of prostate cancer is a problem in clinical practice. We studied the correlation and diagnostic performance of the PSA level with cancer diagnosis, aggressiveness of prostate cancer (Gleason score>7), and bone metastasis.

Methods

A total 1,116 patients who underwent transrectal ultrasound and prostate biopsy were retrospectively studied. The patients were divided into subgroups by baseline PSA level as follows: ≤4, 4.1–10, 10.1–20, 20.1–50, 50.1–100, and >100 ng/mL. The area under the receiver operating characteristic curve (AuROC), sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio of each PSA level were evaluated for correlation and diagnostic performance with positive biopsy, Gleason score for aggressiveness, and bone metastasis.

Results

A positive biopsy result was found in 395 patients (35.39%). The PSA level corresponded well with the diagnosis of prostate cancer and a positive bone scan but moderately well with Gleason score as shown by AuROC for diagnosis of prostate cancer (0.82), positive bone scan (0.88), and Gleason score>7 (0.78). The specificity of a PSA level of 4.1–10, 10.1–20, 21.1–50, 50.1–100, and >100 ng/mL in the diagnosis prostate cancer was 9.3, 55.5, 87.5, 98.2, and 99.7, respectively.

Conclusions

The data showed a strong correlation of PSA level with tumor diagnosis, tumor aggressiveness, and bone metastasis. The prevalence of prostate cancer in this cohort was 35.39%. The chance of diagnosis of prostate cancer was greater than that for benign prostatic hyperplasia when the PSA level was higher than 20 ng/mL.