Modeling grade progression in an active surveillance study

Prostate cancer grade, assessed with the Gleason score, describes how abnormal the tumor tissue and cells appear, and it is an important prognostic indicator of disease progression. Whether prostate tumors change grade is a question that has implications for screening and treatment. Empirical data on tumor grade over time have become available from men biopsied regularly as part of active surveillance (AS). However, biopsy (BX) grade is subject to misclassification. In this article, we develop a model that allows for estimation of the time of grade change while accounting for the misclassification error from BX grade. We use misclassification rates from studies of prostate cancer BXs followed by radical prostatectomy. Estimation of the transition times from true low-grade to high-grade disease is conducted within a Bayesian framework. We apply our model to serial observations on BX grade among 627 cases enrolled in a cohort of AS patients at Johns Hopkins University who were biopsied annually and referred to treatment if there was any evidence of disease progression on BX. We consider different prior distributions for the time to true grade progression. The estimated likelihood of grade progression within 10 years of study entry ranges from 12% to 24% depending on the prior. We conclude that knowledge of rates of grade misclassification allows for determination of true grade progression rates among men with serial BXs on AS. Although our results are sensitive to prior specifications, they indicate that in a nontrivial fraction of the patient population, tumor grade can progress.

Advanced diagnostic breast cancer imaging: variation and patterns of care in Washington state

INTRODUCTION

Because receipt of breast imaging likely occurs in nonrandom patterns, selection bias is an important issue in studies that attempt to elucidate associations between imaging and breast cancer outcomes. The purpose of this study was to analyze use of advanced diagnostic imaging in a cohort of patients with breast cancer insured by commercial, managed care, and public health plans by demographic, health insurance, and clinical variables from 2002 to 2009.

METHODS

We identified women with breast cancer diagnoses from a Surveillance Epidemiology and End Results (SEER) registry whose data could be linked to claims from participating health plans. We examined imaging that occurred between cancer diagnosis and initiation of treatment and classified patients according to receipt of (1) mammography or ultrasound only; (2) breast magnetic resonance imaging (MRI); and (3) other advanced imaging (computed tomography [CT] of the chest, abdoment, and pelvis; positron emission tomography [PET]; or PET-CT). We used logistic regression to identify factors associated with receipt of breast MRI as well as other advanced imaging.

RESULTS

Commercial health plan, younger age, and later year of diagnosis were strongly associated with receipt of breast MRI and other advanced imaging. Women with prescription drug plans and those who had less comorbidities were more likely to have received breast MRI.

CONCLUSION

Use of breast MRI and other advanced imaging is increasing among patients newly diagnosed with breast cancer; individual patient and insurance-related factors are associated with receipt of these imaging tests. Whether use of diagnostic advanced imaging affects outcomes such as re-excision, cancer recurrence, mortality rates, and costs of breast cancer treatment remains to be determined.

Should modest elevations in prostate-specific antigen, International Prostate Symptom Score, or their rates of increase over time be used as surrogate measures of incident benign prostatic hyperplasia?

Although surrogate measures of benign prostatic hyperplasia (BPH) are often used in epidemiologic studies, their performance characteristics are unknown. Using data from the Prostate Cancer Prevention Trial (n = 5,986), we evaluated prostate-specific antigen (PSA), International Prostate Symptom Score (IPSS), and their rates of change as predictors of incident BPH. BPH (n = 842 cases) was defined as medical or surgical treatment or at least 2 IPSS of 15 or higher. Proportional hazards models were used to measure the associations of baseline PSA, IPSS, and their velocities over 2 years with BPH risk, and time-dependent receiver-operating characteristic curves were used to measure their discriminatory performance. Unit increases in PSA, IPSS, and IPSS velocity were associated with 34%, 35%, and 29% (all P < 0.001) increases in BPH risk, respectively. The areas under the receiver-operating characteristic curves were significantly greater than 0.5 for PSA (0.58, 95% confidence interval (CI): 0.56, 0.60), IPSS (0.77, 95% CI: 0.75, 0.78), and IPSS velocity (0.63, 95% CI: 0.61, 0.65); however there were no cut points at which sensitivity and specificity were both above 75%. We concluded that moderate elevations in PSA, IPSS, or their rates of change should not be used as surrogate measures of incident BPH.

Influence of study features and methods on overdiagnosis estimates in breast and prostate cancer screening

Knowledge of the likelihood that a screening-detected case of cancer has been overdiagnosed is vitally important to make treatment decisions and develop screening policy. An overdiagnosed case is an excess case detected by screening. Estimates of the frequency of overdiagnosis in breast and prostate cancer screening vary greatly across studies. This article identifies features of overdiagnosis studies that influence results and shows their effect by using published research. First, different ways to define and measure overdiagnosis are considered. Second, contextual features and how they affect overdiagnosis estimates are examined. Third, the effect of estimation approach is discussed. Many studies use excess incidence under screening as a proxy for overdiagnosis. Others use statistical models to make inferences about lead time or natural history and then derive the corresponding fraction of cases that are overdiagnosed. This article concludes with questions that readers of overdiagnosis studies can use to evaluate the validity and relevance of published estimates and recommends that authors of studies quantifying overdiagnosis provide information about these features.

Early detection of prostate cancer: AUA Guideline

PURPOSE

The guideline purpose is to provide the urologist with a framework for the early detection of prostate cancer in asymptomatic average risk men.

MATERIALS AND METHODS

A systematic review was conducted and summarized evidence derived from over 300 studies that addressed the predefined outcomes of interest (prostate cancer incidence/mortality, quality of life, diagnostic accuracy and harms of testing). In addition to the quality of evidence, the panel considered values and preferences expressed in a clinical setting (patient-physician dyad) rather than having a public health perspective. Guideline statements were organized by age group in years (age <40; 40 to 54; 55 to 69; ≥ 70).

RESULTS

Except prostate specific antigen-based prostate cancer screening, there was minimal evidence to assess the outcomes of interest for other tests. The quality of evidence for the benefits of screening was moderate, and evidence for harm was high for men age 55 to 69 years. For men outside this age range, evidence was lacking for benefit, but the harms of screening, including over diagnosis and overtreatment, remained. Modeled data suggested that a screening interval of two years or more may be preferred to reduce the harms of screening.

CONCLUSIONS

The Panel recommended shared decision-making for men age 55 to 69 years considering PSA-based screening, a target age group for whom benefits may outweigh harms. Outside this age range, PSA-based screening as a routine could not be recommended based on the available evidence.

Limitations of basing screening policies on screening trials: The US Preventive Services Task Force and Prostate Cancer Screening

BACKGROUND

The US Preventive Services Task Force recently recommended against prostate-specific antigen screening for prostate cancer based primarily on evidence from the European Randomized Study of Screening for Prostate Cancer (ERSPC) and the US Prostate, Lung, Colorectal, and Ovarian (PLCO) cancer screening trial.

OBJECTIVE

: To examine limitations of basing screening policy on evidence from screening trials.

METHODS

We reviewed published modeling studies that examined population and trial data. The studies (1) project the roles of screening and changes in primary treatment in the US mortality decline; (2) extrapolate the ERSPC mortality reduction to the long-term US setting; (3) estimate overdiagnosis based on US incidence trends; and (4) quantify the impact of control arm screening on PLCO mortality results.

RESULTS

Screening plausibly explains 45% and changes in primary treatment can explain 33% of the US prostate cancer mortality decline. Extrapolating the ERSPC results to the long-term US setting implies an absolute mortality reduction at least 5 times greater than that observed in the trial. Approximately 28% of screen-detected cases are overdiagnosed in the United States versus 58% of screen-detected cases suggested by the ERSPC results. Control arm screening can explain the null result in the PLCO trial.

CONCLUSIONS

Modeling studies indicate that population trends and trial results extended to the long-term population setting are consistent with greater benefit of prostate-specific antigen screening-and more favorable harm-benefit tradeoffs-than has been suggested by empirical trial evidence.

American Cancer Society lung cancer screening guidelines

Findings from the National Cancer Institute's National Lung Screening Trial established that lung cancer mortality in specific high-risk groups can be reduced by annual screening with low-dose computed tomography. These findings indicate that the adoption of lung cancer screening could save many lives. Based on the results of the National Lung Screening Trial, the American Cancer Society is issuing an initial guideline for lung cancer screening. This guideline recommends that clinicians with access to high-volume, high-quality lung cancer screening and treatment centers should initiate a discussion about screening with apparently healthy patients aged 55 years to 74 years who have at least a 30-pack-year smoking history and who currently smoke or have quit within the past 15 years. A process of informed and shared decision-making with a clinician related to the potential benefits, limitations, and harms associated with screening for lung cancer with low-dose computed tomography should occur before any decision is made to initiate lung cancer screening. Smoking cessation counseling remains a high priority for clinical attention in discussions with current smokers, who should be informed of their continuing risk of lung cancer. Screening should not be viewed as an alternative to smoking cessation.

Effects of screening on radical prostatectomy efficacy: the prostate cancer intervention versus observation trial

BACKGROUND

The Scandinavian Prostate Cancer Group Study Number 4 (SPCG-4) trial showed that radical prostatectomy (RP) reduced prostate cancer deaths with an absolute mortality difference (AMD) between the RP and watchful waiting arms of 6.1% (95% confidence interval [CI] = 0.2% to 12.0%) after 15 years. In the United States, the Prostate Cancer Intervention Versus Observation Trial (PIVOT) produced an AMD of 3% (95% CI = -1.1% to 6.5%) after 12 years. It is not known whether a higher frequency of screen detection in PIVOT explains the lower AMD.

METHODS

We assumed the SPCG-4 trial represents RP efficacy and prostate cancer survival in an unscreened population. Given the fraction of screen-detected prostate cancers in PIVOT, we adjusted prostate cancer survival using published estimates of overdiagnosis and lead time to project the effect of screen detection on disease-specific deaths.

RESULTS

On the basis of published estimates, we assumed that 32% of screen-detected cancers were overdiagnosed and a mean lead time among non-overdiagnosed cancers of 7.7 years. When we adjusted prostate cancer survival for the 76% of case patients in PIVOT who were screen detected, we projected that the AMD after 12 years would be 2.0% (95% CI = -1.6% to 5.6%) based on variation in published estimates of overdiagnosis and mean lead time in the United States.

CONCLUSIONS

If RP efficacy and prostate cancer survival in the absence of screening are similar to that in the SPCG-4 trial, then overdiagnosis and lead time largely explain the lower AMD in PIVOT. If these artifacts of screening are the correct explanation, then there is a subset of case subjects that should not be treated with RP, and identifying this subset should lead to a clearer understanding of the benefit of RP in the remaining cases.

Comparative effectiveness of alternative prostate-specific antigen--based prostate cancer screening strategies: model estimates of potential benefits and harms

BACKGROUND

The U.S. Preventive Services Task Force recently concluded that the harms of existing prostate-specific antigen (PSA) screening strategies outweigh the benefits.

OBJECTIVE

To evaluate comparative effectiveness of alternative PSA screening strategies.

DESIGN

Microsimulation model of prostate cancer incidence and mortality quantifying harms and lives saved for alternative PSA screening strategies.

DATA SOURCES

National and trial data on PSA growth, screening and biopsy patterns, incidence, treatment distributions, treatment efficacy, and mortality.

TARGET POPULATION

A contemporary cohort of U.S. men.

TIME HORIZON

Lifetime.

PERSPECTIVE

Societal.

INTERVENTION

35 screening strategies that vary by start and stop ages, screening intervals, and thresholds for biopsy referral.

OUTCOME MEASURES

PSA tests, false-positive test results, cancer detected, overdiagnoses, prostate cancer deaths, lives saved, and months of life saved.

RESULTS OF BASE-CASE ANALYSIS

Without screening, the risk for prostate cancer death is 2.86%. A reference strategy that screens men aged 50 to 74 years annually with a PSA threshold for biopsy referral of 4 µg/L reduces the risk for prostate cancer death to 2.15%, with risk for overdiagnosis of 3.3%. A strategy that uses higher PSA thresholds for biopsy referral in older men achieves a similar risk for prostate cancer death (2.23%) but reduces the risk for overdiagnosis to 2.3%. A strategy that screens biennially with longer screening intervals for men with low PSA levels achieves similar risks for prostate cancer death (2.27%) and overdiagnosis (2.4%), but reduces total tests by 59% and false-positive results by 50%.

RESULTS OF SENSITIVITY ANALYSIS

Varying incidence inputs or reducing the survival improvement due to screening did not change conclusions.

LIMITATION

The model is a simplification of the natural history of prostate cancer, and improvement in survival due to screening is uncertain.

CONCLUSION

Compared with standard screening, PSA screening strategies that use higher thresholds for biopsy referral for older men and that screen men with low PSA levels less frequently can reduce harms while preserving lives.

PRIMARY FUNDING SOURCE

National Cancer Institute and Centers for Disease Control and Prevention.

Biological correlates of biochemical recurrence free survival using multiple markers in a large tissue microarray cohort

BACKGROUND

High-throughput analyses yielded a large number of predictive biomarkers in prostatic cancer (PCa) patients. Combinations of these biomarkers and with clinical features could improve on prediction.

MATERIALS AND METHODS

Tissue microarrays (640 patients) with triplicate cores of non-neoplastic prostate, benign prostatic hyperplasia (BPH), and index tumor were immunostained with antibodies to numerous biomarkers, digitized, and quantified. We used tree-based classification algorithms to stratify patients into 3 risk strata on the basis of their clinical and pathologic data. Markers were tested for prognostic ability in each stratum (stratum 1 had <10% risk of recurrence; stratum 3 had >60% likelihood of recurrence over a period >12 years). Sub stratification of the clinico-pathologic strata was also pursued.

RESULTS

We identified a number of significant predictors for PSA recurrence free survival, which were used to construct a predictive model that combines clinical and biomarker data. In the low-risk clinico-pathologic stratum, the markers were predominantly related to non-neoplastic tissues, in the moderate-risk stratum to stromal-epithelial interactions and angiogenesis, while those in the high-risk stratum were mostly oncogenes. Substratification of the intermediate risk group using stromal quantitation and proliferative index successfully, up or down, staged the risk strata for most patients.

CONCLUSIONS

The fact that different biomarkers are most predictive of disease recurrence within different risk subgroups suggests an association between biological processes and prognostic ability. This is the first time that subgroup analysis of markers finds that prognostic ability is associated with biological processes and is proof of concept that distinct phenotypes are associated with risk of recurrence in different types of cancer.

Deriving benefit of early detection from biomarker-based prognostic models

Many prognostic models for cancer use biomarkers that have utility in early detection. For example, in prostate cancer, models predicting disease-specific survival use serum prostate-specific antigen levels. These models typically show that higher marker levels are associated with poorer prognosis. Consequently, they are often interpreted as indicating that detecting disease at a lower threshold of the biomarker is likely to generate a survival benefit. However, lowering the threshold of the biomarker is tantamount to early detection. For survival benefit to not be simply an artifact of starting the survival clock earlier, we must account for the lead time of early detection. It is not known whether the existing prognostic models imply a survival benefit under early detection once lead time has been accounted for. In this article, we investigate survival benefit implied by prognostic models where the predictor(s) of disease-specific survival are age and/or biomarker level at disease detection. We show that the benefit depends on the rate of biomarker change, the lead time, and the biomarker level at the original date of diagnosis as well as on the parameters of the prognostic model. Even if the prognostic model indicates that lowering the threshold of the biomarker is associated with longer disease-specific survival, this does not necessarily imply that early detection will confer an extension of life expectancy.

Abstract FO01-01: Estimating how many prostate cancers are overdiagnosed: Overcoming challenges and avoiding mistakes

Despite the promise of the PSA test for early detection of prostate cancer, it is now clear that PSA screening can be costly, generating harms alongside benefits. Overdiagnosis, or the detection of cancers that would never have been detected clinically, is perhaps the harm of greatest concern in PSA screening. However, different studies provide widely varying assessments of the magnitude of the overdiagnosis problem. A report from the European prostate screening trial estimated that 48 men would have to be overdiagnosed to prevent one prostate cancer death, and a report based on US incidence trends estimated that more than one million men had been overdiagnosed and overtreated by 2005. These statistics are alarming but dramatically overstate the problem. In this presentation I will demonstrate how different definitions, methods and even populations can produce very different, and sometimes inaccurate, assessments of the frequency of overdiagnosis associated with PSA screening. I will present results from two studies of the US population that showed that about one in four men over 50 detected by PSA screening prior to 2000 was overdiagnosed. I will also present personalized estimates of the likelihood of overdiagnosis that vary from from 3 to 80% depending on age, grade and PSA. These estimates can be used in designing population screening programs that reduce costs and harms while preserving benefit.

Citation Format: Ruth Etzioni. Estimating how many prostate cancers are overdiagnosed: Overcoming challenges and avoiding mistakes. [abstract]. In: Proceedings of the Eleventh Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2012 Oct 16-19; Anaheim, CA. Philadelphia (PA): AACR; Cancer Prev Res 2012;5(11 Suppl):Abstract nr FO01-01.

Prostate cancer mortality following active surveillance versus immediate radical prostatectomy

PURPOSE

[corrected] Active surveillance has been endorsed for low-risk prostate cancer, but information about long-term outcomes and comparative effectiveness of active surveillance is lacking. The purpose of this study is to project prostate cancer mortality under active surveillance followed by radical prostatectomy versus under immediate radical prostatectomy.

EXPERIMENTAL DESIGN

A simulation model was developed to combine information on time from diagnosis to treatment under active surveillance and associated disease progression from a Johns Hopkins active surveillance cohort (n = 769), time from radical prostatectomy to recurrence from cases in the CaPSURE database with T-stage ≤ T2a (n = 3,470), and time from recurrence to prostate cancer death from a T-stage ≤ T2a Johns Hopkins cohort of patients whose disease recurred after radical prostatectomy (n = 963). Results were projected for a hypothetical cohort aged 40 to 90 years with low-risk prostate cancer (T-stage ≤ T2a, Gleason score ≤ 6, and prostate-specific antigen level ≤ 10 ng/mL).

RESULTS

The model projected that 2.8% of men on active surveillance and 1.6% of men with immediate radical prostatectomy would die of their disease in 20 years. Corresponding lifetime estimates were 3.4% for active surveillance and 2.0% for immediate radical prostatectomy. The average projected increase in life expectancy associated with immediate radical prostatectomy was 1.8 months. On average, the model projected that men on active surveillance would remain free of treatment for an additional 6.4 years relative to men treated immediately.

CONCLUSIONS

Active surveillance is likely to produce a very modest decline in prostate cancer-specific survival among men diagnosed with low-risk prostate cancer but could lead to significant benefits in terms of quality of life.

Increasing use of radical prostatectomy for nonlethal prostate cancer in Sweden

PURPOSE

The number of patients in Sweden treated with radical prostatectomy for localized prostate cancer has increased exponentially. The extent to which this increase reflects treatment of nonlethal disease detected through prostate-specific antigen (PSA) screening is unknown.

EXPERIMENTAL DESIGN

We undertook a nationwide study of all 18,837 patients with prostate cancer treated with radical prostatectomy in Sweden from 1988 to 2008 with complete follow-up through 2009. We compared cumulative incidence curves, fit Cox regression and cure models, and conducted a simulation study to determine changes in treatment of nonlethal cancer, in cancer-specific survival over time, and effect of lead-time due to PSA screening.

RESULTS

The annual number of radical prostatectomies increased 25-fold during the study period. The 5-year cancer-specific mortality rate decreased from 3.9% [95% confidence interval (CI), 2.5-5.3] among patients diagnosed between 1988 and 1992 to 0.7% (95% CI, 0.4-1.1) among those diagnosed between 1998 and 2002 (P(trend) < 0.001). According to the cure model, the risk of not being cured declined by 13% (95% CI, 12%-14%) with each calendar year. The simulation study indicated that only about half of the improvement in disease-specific survival could be accounted for by lead-time.

CONCLUSION

Patients overdiagnosed with nonlethal prostate cancer appear to account for a substantial and growing part of the dramatic increase in radical prostatectomies in Sweden, but increasing survival rates are likely also due to true reductions in the risk of disease-specific death over time. Because the magnitude of harm and costs due to overtreatment can be considerable, identification of men who likely benefit from radical prostatectomy is urgently needed.

The prostate cancer conundrum revisited: treatment changes and prostate cancer mortality declines

BACKGROUND

Prostate cancer mortality rates in the United States declined by >40% between 1991 and 2005. The impact of changes in primary treatment and adjuvant and neoadjuvant hormone therapy on this decline is unknown.

METHODS

The authors applied 3 independently developed models of prostate cancer natural history and disease detection under common assumptions about treatment patterns, treatment efficacy, and survival in the population. Primary treatment patterns were derived from the Surveillance, Epidemiology, and End Results registry; data on the frequency of hormone therapy were obtained from the CaPSURE (Cancer of the Prostate Strategic Urologic Research Endeavor) database; and treatment efficacy was based on estimates from randomized trials and comparative effectiveness studies of treatment alternatives. The models projected prostate cancer mortality without prostate-specific antigen screening and in the presence and absence of treatment benefit. The impact of primary treatment was expressed as a fraction of the difference between observed mortality and projected mortality in the absence of treatment benefit.

RESULTS

The 3 models projected that changes in treatment explained 22% to 33% of the mortality decline by 2005. These contributions were accounted for mostly by surgery and radiation therapy, which increased in frequency until the 1990s, whereas hormone therapies contributed little to the mortality decline by 2005. Assuming that treatment benefit was less for older men, changes in treatment explained only 16% to 23% of the mortality decline by 2005.

CONCLUSIONS

Changes in primary treatment explained a minority of the observed decline in prostate cancer mortality. The remainder of the decline probably was because of other interventions, such as prostate-specific antigen screening and advances in the treatment of recurrent and progressive disease.

The impact of PLCO control arm contamination on perceived PSA screening efficacy

PURPOSE

To quantify the extent to which a clinically significant prostate cancer mortality reduction due to screening could have been masked by control arm screening (contamination) in the Prostate, Lung, Colorectal, and Ovarian (PLCO) trial.

METHODS

We used three independently developed models of prostate cancer natural history to conduct a virtual PLCO trial. Simulated participants underwent pre-trial screening based on population patterns. The intervention arm followed observed compliance during the trial then resumed population screening. A contaminated control arm followed observed contamination during the trial then resumed population screening, while an uncontaminated control arm discontinued screening upon entry. We assumed a clinically significant screening benefit, applied population treatments and survival patterns, and calculated mortality rate ratios relative to the contaminated and uncontaminated control arms.

RESULTS

The virtual trial reproduced observed incidence, including stage and grade distributions, and control arm mortality after 10 years of complete follow-up. Under the assumed screening benefit, the three models found that contamination increased the mortality rate ratio from 0.68-0.77 to 0.86-0.91, increased the chance of excess mortality in the intervention arm from 0-4 % to 15-28 %, and decreased the power of the trial to detect a mortality difference from 40-70 % to 9-25 %.

CONCLUSIONS

Our computer simulation models indicate that contamination substantially limited the ability of the PLCO to identify a clinically significant screening benefit. While the trial shows annual screening does not reduce mortality relative to population screening, contamination prevents concluding whether screening reduces mortality relative to no screening.

Biopsy follow-up of prostate-specific antigen tests

BACKGROUND

A prostate-specific antigen (PSA) level above 4 ng/mL has historically been recognized as an appropriate threshold to recommend biopsy; however the risk of high-grade disease observed among men with lower PSA levels in the Prostate Cancer Prevention Trial has led to calls to change the criteria for biopsy referral.

PURPOSE

To aid providers when discussing aggressiveness of biopsy by cataloging available community biopsy patterns and determine whether lower PSA thresholds are being used to recommend biopsy.

METHODS

Laboratory and biopsy records were reviewed among 59,764 men in a large Washington State health plan between 1998 and 2007. Follow-up in the 12-month period after a test was categorized as biopsy, urology visit without biopsy, additional PSA testing with no urology visit, or no PSA-related follow-up. Data analysis occurred between 2010 and 2011.

RESULTS

Twenty-eight percent of tests with PSA levels ≥4.0 ng/mL, 2.9% of tests with levels between 2.5 and 4.0 ng/mL, and 0.4% of tests with levels <2.5 ng/mL were followed with a biopsy within 12 months. More than 40% of elevated tests (≥4.0 ng/mL) were followed by a urologist visit without a biopsy, and more than 30% of tests ≥4.0 did not have any PSA-related follow-up within 12 months. PSA velocity, defined as annualized rate of change in PSA level, was strongly associated with biopsy, especially when absolute PSA was <4.0 ng/mL. There appear to be no discernable temporal trends in biopsy thresholds or practice patterns based on PSA lower levels or velocity.

CONCLUSIONS

Despite recent calls to more aggressively recommend biopsy at lower PSA thresholds, the practice in this large health plan has remained consistent over time.

Long-term projections of the harm-benefit trade-off in prostate cancer screening are more favorable than previous short-term estimates

OBJECTIVE

To project long-term estimates of the number needed to screen (NNS) and the additional number needed to treat (NNT) to prevent one prostate cancer death with prostate-specific antigen (PSA) screening in Europe and in the United States.

STUDY DESIGN AND SETTING

A mathematical model of disease-specific deaths in screened and unscreened men given information on overdiagnosis, disease-specific survival in the absence of screening, screening efficacy, and other-cause mortality is presented. A simulation framework is used to incorporate competing causes of death.

RESULTS

Assuming overdiagnosis and screening efficacy consistent with European Randomized study of Screening for Prostate Cancer (ERSPC) results, we project that, after 25 years, 262 men need to be screened and nine additional men need to be screen detected to prevent one prostate cancer death. Corresponding estimates of the NNS and the additional NNT under a range of overdiagnosis rates that are consistent with U.S. incidence are 186-220 and 2-5.

CONCLUSIONS

Long-term estimates of the NNS and the additional NNT are an order of magnitude lower than the short-term estimates published with the results of the ERSPC trial and may be consistent with cost-effective PSA screening in the general U.S. population.

What if I don't treat my PSA-detected prostate cancer? Answers from three natural history models

BACKGROUND

Making an informed decision about treating a prostate cancer detected after a routine prostate-specific antigen (PSA) test requires knowledge about disease natural history, such as the chances that it would have been clinically diagnosed in the absence of screening and that it would metastasize or lead to death in the absence of treatment.

METHODS

We use three independently developed models of prostate cancer natural history to project risks of clinical progression events and disease-specific deaths for PSA-detected cases assuming they receive no primary treatment.

RESULTS

The three models project that 20%-33% of men have preclinical onset; of these 38%-50% would be clinically diagnosed and 12%-25% would die of the disease in the absence of screening and primary treatment. The risk that men age less than 60 at PSA detection with Gleason score 2-7 would be clinically diagnosed in the absence of screening is 67%-93% and would die of the disease in the absence of primary treatment is 23%-34%. For Gleason score 8 to 10 these risks are 90%-96% and 63%-83%.

CONCLUSIONS

Risks of disease progression among untreated PSA-detected cases can be nontrivial, particularly for younger men and men with high Gleason scores. Model projections can be useful for informing decisions about treatment.

IMPACT

This is the first study to project population-based natural history summaries in the absence of screening or primary treatment and risks of clinical progression events following PSA detection in the absence of primary treatment.

Depression and incident lower limb amputations in veterans with diabetes

PROBLEM

Depression is associated with a higher risk of macrovascular and microvascular complications and mortality in diabetes, but whether depression is linked to an increased risk of incident amputations is unknown. We examined the association between diagnosed depression and incident non-traumatic lower limb amputations in veterans with diabetes.

METHODS

This was a retrospective cohort study from 2000-2004 that included 531,973 veterans from the Diabetes Epidemiology Cohorts, a national Veterans Affairs (VA) registry with VA and Medicare data. Depression was defined by diagnostic codes or antidepressant prescriptions. Amputations were defined by diagnostic and procedural codes. We determined the HR and 95% CI for incident non-traumatic lower limb amputation by major (transtibial and above) and minor (ankle and below) subtypes, comparing veterans with and without diagnosed depression and adjusting for demographics, health care utilization, diabetes severity and comorbid medical and mental health conditions.

RESULTS

Over a mean 4.1 years of follow-up, there were 1289 major and 2541 minor amputations. Diagnosed depression was associated with an adjusted HR of 1.33 (95% CI: 1.15-1.55) for major amputations. There was no statistically significant association between depression and minor amputations (adjusted HR 1.01, 95% CI: 0.90-1.13).

CONCLUSIONS

Diagnosed depression is associated with a 33% higher risk of incident major lower limb amputation in veterans with diabetes. Further study is needed to understand this relationship and to determine whether depression screening and treatment in patients with diabetes could decrease amputation rates.

Influence of publication of US and European prostate cancer screening trials on PSA testing practices

In 2009, results from the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial indicated no difference in mortality between the screening and the control groups (rate ratio = 1.13, 95% confidence interval = 0.75 to 1.70), whereas those from the European Randomized study of Screening for Prostate Cancer trial indicated a 20% reduction in mortality among the screening group (rate ratio = 0.80, 95% confidence interval = 0.65 to 0.98). In this study, we examined whether prostate-specific antigen (PSA) testing has changed following these publications. The primary outcome measure was the proportion of men seen at least once in a primary care or urology clinic between August 1, 2004, and March 31, 2010, who received a PSA test. Following the publications, PSA use declined slightly-by 3.0 percentage points and 2.7 percentage points among men aged 40-54 and 55-74 years, respectively. PSA testing among men older than 75 years initially declined slightly following the recommendations by the US Preventive Services Task Force in 2008 and continued to decline after the trial publications.