Identifying and characterizing “escapes”-men who develop metastases or die from prostate cancer despite screening (ERSPC, section Rotterdam)

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.

The Finnish prostate cancer screening trial: analyses on the screening failures

Prostate cancer (PC) screening with prostate-specific antigen (PSA) has been shown to decrease PC mortality in the European Randomized Study of Screening for Prostate Cancer (ERSPC). However, in the Finnish trial, which is the largest component of the ERSPC, no statistically significant mortality reduction was observed. We investigated which had the largest impact on PC deaths in the screening arm: non-participation, interval cancers or PSA threshold. The screening (SA) and control (CA) arms comprised altogether 80,144 men. Men in the SA were screened at four-year intervals and referred to biopsy if the PSA concentration was ≥ 4.0 ng/ml, or 3.0-3.99 ng/ml with a free/total PSA ratio ≤ 16%. The median follow-up was 15.0 years. A counterfactual exclusion method was applied to estimate the effect of three subgroups in the SA: the non-participants, the screen-negative men with PSA ≥ 3.0 ng/ml and a subsequent PC diagnosis, and the men with interval PCs. The absolute risk of PC death was 0.76% in the SA and 0.85% in the CA; the observed hazard ratio (HR) was 0.89 (95% confidence interval (CI) 0.76-1.04). After correcting for non-attendance, the HR was 0.78 (0.64-0.96); predicted effect for a hypothetical PSA threshold of 3.0 ng/ml the HR was 0.88 (0.74-1.04) and after eliminating the effect of interval cancers the HR was 0.88 (0.74-1.04). Non-participating men in the SA had a high risk of PC death and a large impact on PC mortality. A hypothetical lower PSA threshold and elimination of interval cancers would have had a less pronounced effect on the screening impact.

Screening for prostate cancer: current status of ERSPC and screening-related issues

The "European Randomized Study of Screening for Prostate Cancer" (ERSPC) was initiated in 1993 and up to 1998 six other European countries were joined. The main goal is to establish the effect of Prostate Specific Antigen (PSA)-based screening on prostate cancer (PCa) mortality with morbidity as secondary end point. At present, with 11 and 12 years of follow-up significant relative reductions of 21 % and 31 % relating to both end points have been reported. The diagnosis of non-life threatening PCA (over diagnosis) is estimated to be in the range of 50 % and represents the main "harm", which prevents the introduction of population-based screening. As a result, the prevention of over diagnosis is now given top research priority. PSA as a screening test has poor performance characteristics including a low specificity. With the cut-off value of 3.0 ng/ml chosen within ERSPC, about 25 % of men aged 55--69 test positively, 75 % have "negative" test results, which do not definitely exclude the presence of PCa. Research to establish empirical schemes of follow-up based on PSA levels and other parameters are ongoing worldwide. In the meantime, we are, by approximation, capable to identify over diagnosed PCa detected by screening. Active surveillance can be applied to avoid side effects and expenses of treatment and is, among others, based on the grade of differentiation determined on biopsies. The assignment of the most favorable "Gleason score 6" is a crucial decision element. Unfortunately, biopsy pathology underestimates the true degree of PC aggressiveness by 25--30 % which establishes the need of careful follow-up.

Population-based analysis of prostate-specific antigen (PSA) screening in younger men (<55 years) in Australia

OBJECTIVE

To analyse the trends in opportunistic PSA screening in Australia, focusing on younger men (<55 years of age), to examine the effects of this screening on transrectal ultrasonography (TRUS)-guided biopsy rates and to determine the nature of prostate cancers (PCas) being detected.

SUBJECTS AND METHODS

All men who received an opportunistic screening PSA test and TRUS-guided biopsy between 2001 and 2008 in Australia were analysed using data from the Australian Cancer registry (Australian Institute of Health and Welfare) and Medicare databases. The Victorian cancer registry was used to obtain Gleason scores. Age-standardized and age-specific rates were calculated, along with the incidence of PCa, and correlated with Gleason scores.

RESULTS

A total 5 174 031 PSA tests detected 128 167 PCas in the period 2001-2008. During this period, PSA testing increased by 146% (a mean of 4629 tests per 100 000 men annually), with 80 and 59% increases in the rates of TRUS-guided biopsy and incidence of PCa, respectively. The highest increases in PSA screening occurred in men <55 years old and up to 1101 men had to be screened to detect one incident case of PCa (0.01%). Screening resulted in two thirds of men aged <55 years receiving a negative TRUS biopsy. There was no correlation with Gleason >7 tumours in patients aged <55 years.

CONCLUSION

Despite the ongoing controversy about the merits of PCa screening, there was an increase in PSA testing, especially in men <55 years old, leading to a modestly higher incidence of PCa in Australia. Overall, PSA screening was associated with high rates of negative TRUS-biopsy and the detection of low/intermediate grade PCa among younger patients.

Variable metastatic potentials correlate with differential plectin and vimentin expression in syngeneic androgen independent prostate cancer cells

Prostate cancer is a clinically heterogeneous disease, ranging from indolent asymptomatic disease to very aggressive metastatic and life threatening forms of the disease. Distant metastasis represents the major lethal cause of prostate cancer. The most critical clinical challenge in the management of the patients is identifying those individuals at risk of developing metastatic disease. To understand the molecular mechanisms of prostate cancer metastasis and identify markers with metastatic potential, we have analyzed protein expression in two syngeneic prostate cancer cells lines PC3-N2 and PC3-ML2 using isobaric tags for relative and absolute quantitation labeling and multi-dimensional protein identification technology liquid chromatography matrix assisted laser desorption ionization tandem mass spectrometry. PC3-N2 is lowly metastatic while PC3-ML2 highly metastatic. A total of 1,756 proteins were identified in the analyses with 130 proteins showing different expression levels (p<0.01) in the two cell lines. Out of these, 68 proteins were found to be significantly up-regulated while 62 are significantly down-regulated in PC3-ML2 cells compared with PC3-N2 cells. The upregulation of plectin and vimentin which were the most significantly differentially expressed were validated by Western blot and their functional relevance with respect to invasion and migration was determined by siRNA gene silencing. To our knowledge, this study is the first to demonstrate that up-regulation of vimentin and plectin expression positively correlates with the invasion and metastasis of androgen-independent PCA.

Screening for prostate cancer

BACKGROUND

Any form of screening aims to reduce disease-specific and overall mortality, and to improve a person's future quality of life. Screening for prostate cancer has generated considerable debate within the medical and broader community, as demonstrated by the varying recommendations made by medical organizations and governed by national policies. To better inform individual patient decision-making and health policy decisions, we need to consider the entire body of data from randomised controlled trials (RCTs) on prostate cancer screening summarised in a systematic review. In 2006, our Cochrane review identified insufficient evidence to either support or refute the use of routine mass, selective, or opportunistic screening for prostate cancer. An update of the review in 2010 included three additional trials. Meta-analysis of the five studies included in the 2010 review concluded that screening did not significantly reduce prostate cancer-specific mortality. In the past two years, several updates to studies included in the 2010 review have been published thereby providing the rationale for this update of the 2010 systematic review.

OBJECTIVES

To determine whether screening for prostate cancer reduces prostate cancer-specific mortality or all-cause mortality and to assess its impact on quality of life and adverse events.

SEARCH METHODS

An updated search of electronic databases (PROSTATE register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, CANCERLIT, and the NHS EED) was performed, in addition to handsearching of specific journals and bibliographies, in an effort to identify both published and unpublished trials.

SELECTION CRITERIA

All RCTs of screening versus no screening for prostate cancer were eligible for inclusion in this review.

DATA COLLECTION AND ANALYSIS

The original search (2006) identified 99 potentially relevant articles that were selected for full-text review. From these citations, two RCTs were identified as meeting the inclusion criteria. The search for the 2010 version of the review identified a further 106 potentially relevant articles, from which three new RCTs were included in the review. A total of 31 articles were retrieved for full-text examination based on the updated search in 2012. Updated data on three studies were included in this review. Data from the trials were independently extracted by two authors.

MAIN RESULTS

Five RCTs with a total of 341,342 participants were included in this review. All involved prostate-specific antigen (PSA) testing, with or without digital rectal examination (DRE), though the interval and threshold for further evaluation varied across trials. The age of participants ranged from 45 to 80 years and duration of follow-up from 7 to 20 years. Our meta-analysis of the five included studies indicated no statistically significant difference in prostate cancer-specific mortality between men randomised to the screening and control groups (risk ratio (RR) 1.00, 95% confidence interval (CI) 0.86 to 1.17). The methodological quality of three of the studies was assessed as posing a high risk of bias. The European Randomized Study of Screening for Prostate Cancer (ERSPC) and the US Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial were assessed as posing a low risk of bias, but provided contradicting results. The ERSPC study reported a significant reduction in prostate cancer-specific mortality (RR 0.84, 95% CI 0.73 to 0.95), whilst the PLCO study concluded no significant benefit (RR 1.15, 95% CI 0.86 to 1.54). The ERSPC was the only study of the five included in this review that reported a significant reduction in prostate cancer-specific mortality, in a pre-specified subgroup of men aged 55 to 69 years of age. Sensitivity analysis for overall risk of bias indicated no significant difference in prostate cancer-specific mortality when referring to the meta analysis of only the ERSPC and PLCO trial data (RR 0.96, 95% CI 0.70 to 1.30). Subgroup analyses indicated that prostate cancer-specific mortality was not affected by the age at which participants were screened. Meta-analysis of four studies investigating all-cause mortality did not determine any significant differences between men randomised to screening or control (RR 1.00, 95% CI 0.96 to 1.03). A diagnosis of prostate cancer was significantly greater in men randomised to screening compared to those randomised to control (RR 1.30, 95% CI 1.02 to 1.65). Localised prostate cancer was more commonly diagnosed in men randomised to screening (RR 1.79, 95% CI 1.19 to 2.70), whilst the proportion of men diagnosed with advanced prostate cancer was significantly lower in the screening group compared to the men serving as controls (RR 0.80, 95% CI 0.73 to 0.87). Screening resulted in a range of harms that can be considered minor to major in severity and duration. Common minor harms from screening include bleeding, bruising and short-term anxiety. Common major harms include overdiagnosis and overtreatment, including infection, blood loss requiring transfusion, pneumonia, erectile dysfunction, and incontinence. Harms of screening included false-positive results for the PSA test and overdiagnosis (up to 50% in the ERSPC study). Adverse events associated with transrectal ultrasound (TRUS)-guided biopsies included infection, bleeding and pain. No deaths were attributed to any biopsy procedure. None of the studies provided detailed assessment of the effect of screening on quality of life or provided a comprehensive assessment of resource utilization associated with screening (although preliminary analyses were reported).

AUTHORS' CONCLUSIONS

Prostate cancer screening did not significantly decrease prostate cancer-specific mortality in a combined meta-analysis of five RCTs. Only one study (ERSPC) reported a 21% significant reduction of prostate cancer-specific mortality in a pre-specified subgroup of men aged 55 to 69 years. Pooled data currently demonstrates no significant reduction in prostate cancer-specific and overall mortality. Harms associated with PSA-based screening and subsequent diagnostic evaluations are frequent, and moderate in severity. Overdiagnosis and overtreatment are common and are associated with treatment-related harms. Men should be informed of this and the demonstrated adverse effects when they are deciding whether or not to undertake screening for prostate cancer. Any reduction in prostate cancer-specific mortality may take up to 10 years to accrue; therefore, men who have a life expectancy less than 10 to 15 years should be informed that screening for prostate cancer is unlikely to be beneficial. No studies examined the independent role of screening by DRE.

iTRAQ identification of candidate serum biomarkers associated with metastatic progression of human prostate cancer

A major challenge in the management of patients with prostate cancer is identifying those individuals at risk of developing metastatic disease, as in most cases the disease will remain indolent. We analyzed pooled serum samples from 4 groups of patients (n = 5 samples/group), collected prospectively and actively monitored for a minimum of 5 yrs. Patients groups were (i) histological diagnosis of benign prostatic hyperplasia with no evidence of cancer 'BPH', (ii) localised cancer with no evidence of progression, 'non-progressing' (iii) localised cancer with evidence of biochemical progression, 'progressing', and (iv) bone metastasis at presentation 'metastatic'. Pooled samples were immuno-depleted of the 14 most highly abundant proteins and analysed using a 4-plex iTRAQ approach. Overall 122 proteins were identified and relatively quantified. Comparisons of progressing versus non-progressing groups identified the significant differential expression of 25 proteins (p<0.001). Comparisons of metastatic versus progressing groups identified the significant differential expression of 23 proteins. Mapping the differentially expressed proteins onto the prostate cancer progression pathway revealed the dysregulated expression of individual proteins, pairs of proteins and 'panels' of proteins to be associated with particular stages of disease development and progression. The median immunostaining intensity of eukaryotic translation elongation factor 1 alpha 1 (eEF1A1), one of the candidates identified, was significantly higher in osteoblasts in close proximity to metastatic tumour cells compared with osteoblasts in control bone (p = 0.0353, Mann Whitney U). Our proteomic approach has identified leads for potentially useful serum biomarkers associated with the metastatic progression of prostate cancer. The panels identified, including eEF1A1 warrant further investigation and validation.

Risk-based prostate cancer screening

CONTEXT

Widespread mass screening of prostate cancer (PCa) is not recommended because the balance between benefits and harms is still not well established. The achieved mortality reduction comes with considerable harm such as unnecessary biopsies, overdiagnoses, and overtreatment. Therefore, patient stratification with regard to PCa risk and aggressiveness is necessary to identify those men who are at risk and may actually benefit from early detection.

OBJECTIVE

This review critically examines the current evidence regarding risk-based PCa screening.

EVIDENCE ACQUISITION

A search of the literature was performed using the Medline database. Further studies were selected based on manual searches of reference lists and review articles.

EVIDENCE SYNTHESIS

Prostate-specific antigen (PSA) has been shown to be the single most significant predictive factor for identifying men at increased risk of developing PCa. Especially in men with no additional risk factors, PSA alone provides an appropriate marker up to 30 yr into the future. After assessment of an early PSA test, the screening frequency may be determined based on individualized risk. A limited list of additional factors such as age, comorbidity, prostate volume, family history, ethnicity, and previous biopsy status have been identified to modify risk and are important for consideration in routine practice. In men with a known PSA, risk calculators may hold the promise of identifying those who are at increased risk of having PCa and are therefore candidates for biopsy.

CONCLUSIONS

PSA testing may serve as the foundation for a more risk-based assessment. However, the decision to undergo early PSA testing should be a shared one between the patient and his physician based on information balancing its advantages and disadvantages.