What Is the True Number Needed to Screen and Treat to Save a Life With Prostate-Specific Antigen Testing?

Brady Urological Institute, Johns Hopkins Medical Institutions, Baltimore, MD, USA.
Journal of Clinical Oncology (Impact Factor: 18.43). 02/2011; 29(4):464-7. DOI: 10.1200/JCO.2010.30.6373
Source: PubMed


The European Randomized Study of Screening for Prostate Cancer (ERSPC) reported a 20% mortality reduction with prostate-specific antigen (PSA) screening. However, they estimated a number needed to screen (NNS) of 1,410 and a number needed to treat (NNT) of 48 to prevent one prostate cancer death at 9 years. Although NNS and NNT are useful statistics to assess the benefits and harms of an intervention, in a survival study setting such as the ERSPC, NNS and NNT are time specific, and reporting values at one time point may lead to misinterpretation of results. Our objective was to re-examine the effect of varying follow-up times on NNS and NNT using data extrapolated from the ERSPC report.
On the basis of published ERSPC data, we modeled the cumulative hazard function using a piecewise exponential model, assuming a constant hazard of 0.0002 for the screening and control groups for years 1 to 7 of the trial and different constant rates of 0.00062 and 0.00102 for the screening and control groups, respectively, for years 8 to 12. Annualized cancer detection and drop-out rates were also approximated based on the observed number of individuals at risk in published ERSPC data.
According to our model, the NNS and NNT at 9 years were 1,254 and 43, respectively. Subsequently, NNS decreased from 837 at year 10 to 503 at year 12, and NNT decreased from 29 to 18.
Despite the seemingly simplistic nature of estimating NNT, there is widespread misunderstanding of its pitfalls. With additional follow-up in the ERSPC, if the mortality difference continues to grow, the NNT to save a life with PSA screening will decrease.

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    • "The weights given to the pros and cons of prostatespecific antigen (PSA) screening are crucial and, at the same time, time dependent and very subjective. The still-large numbers of men that need to be invited (936) and managed (33) [2] will likely decline with increasing follow-up [3] [4]. More definite data will become available once the ongoing randomized controlled trials of screening have reached a stage where almost all participants are dead. "

    Full-text · Article · Jan 2014 · European Urology
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    • "c o m treatment will not experience a survival benefit. The European Randomized Study of Screening for Prostate Cancer demonstrated that although radical treatment did save lives, there was a significant amount of overtreatment [3]. In addition, about one-third of PCa cases diagnosed in the contemporary period have a low or very low risk of cancer progression [4]. "
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    ABSTRACT: Limited data are currently available regarding the outcomes of radical prostatectomy (RP) in men with low-risk prostate cancer who were initially managed by active surveillance (AS). To evaluate the pathologic outcomes of patients who underwent RP following initial AS. We analyzed the records of 67 patients who underwent RP following initial AS begun between 1993 and 2011. All patients underwent confirmatory biopsy to reassess eligibility for AS. RP was recommended for disease progression suggested by follow-up biopsies or imaging. Unfavorable disease was defined as having at least one of the following pathologic findings: Gleason score (GS) ≥4+3, extracapsular extension of tumor, seminal vesicle invasion, or lymph node involvement. A descriptive analysis was performed to assess pathologic features. Median time from confirmatory biopsy to RP was 1.7 yr (range: 0.3-7.8). Reasons for discontinuing AS to undergo RP included evidence of increased tumor volume or grade on follow-up biopsy, patient preference/anxiety, and findings on follow-up imaging in 46 patients (68.7%), 17 patients (25.3%), and 4 patients (6.0%), respectively. Pathologic analyses revealed organ-confined disease in 55 patients (82.1%), and GS was ≥4+3 in 9 (13.4%). Positive nodes were observed in three patients (4.4%) and positive surgical margin in two (3.0%). Overall, 19 patients (28.4%) had unfavorable disease. Of the biopsy criteria for triggering RP, Gleason patterns >3 were the most frequently associated with unfavorable disease (43.3%). One patient (1.5%) experienced biochemical recurrence during postoperative follow-up (median: 3.2 yr). Our study may be limited by its retrospective and single-institution nature. Most patients who started initially on AS after undergoing confirmatory biopsy showed pathologically organ-confined disease with a low GS at RP. Such findings provide further evidence that, overall, AS is a safe treatment approach.
    Full-text · Article · Aug 2013 · European Urology
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    • "Of note, this study had longer follow-up and studied younger men than the ERSPC. These findings were similar to those reported in a projected ERSPC analysis (numbers needed to screen and treat were 837 and 29 at 10 yr and 503 and 18 at 12 yr, respectively) [5]. "

    Full-text · Article · Oct 2011 · European Urology
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