Modeling the impact of the decline in distant stage disease on prostate carcinoma mortality rates

Short-term Endpoints for Cancer Screening Trials: Does Tumor Subtype Matter?

Multicancer early detection tests are precipitating a reexamination of potential short-term endpoints for cancer screening trials. A reduction in advanced stage incidence is a prime candidate, and stage-shift models that substitute early-stage for late-stage survival have been used to predict mortality reduction due to screening. However, standard stage-shift models often ignore prognostic subtypes, effectively implying that cancers detected early also have an associated subtype shift. To illustrate the differences between mortality predictions from stage-shift models that ignore versus preserve prognostic subtype, we use ovarian cancer partitioned by histologic subtype and prostate cancer partitioned by grade. We infer general conditions under which stage-shift models that preserve prognostic subtype are likely to predict mortality reductions that differ from those that ignore subtype and examine the implications for short-term endpoints based on stage in cancer screening trials.

Stage Shift as an Endpoint in Cancer Screening Trials: Implications for Evaluating Multicancer Early Detection Tests

BACKGROUND

Disease-specific mortality is a consensus endpoint in cancer screening trials. New liquid biopsy-based screening tests, including multi-cancer early detection (MCED) tests, are creating a need to reduce the typically lengthy screening trial process. Endpoints based on the reduction in late-stage disease (stage shift) have been proposed but it is unclear how well they predict the impact of screening on disease-specific mortality across a variety of cancers potentially detectable by MCED tests.

METHODS

We develop a mathematical formulation relating the reduction in late-stage cancer to the expected reduction in disease-specific mortality if cases diagnosed early via screening receive a corresponding shift in mortality. We investigate the similarity between the expected mortality reduction and the observed mortality reduction in published trials of screening for breast, lung, ovarian, and prostate cancer.

RESULTS

The expected mortality reduction for a given stage shift varies significantly depending on cancer- and stage-specific survival distributions, with some cancer types showing little possibility for mortality improvement even under substantial stage shift. The expected mortality reduction fails to consistently match the mortality outcomes of published trials.

CONCLUSIONS

In MCED, any mortality benefit is likely to vary substantially across target cancers. Stage shift does not appear to be a reliable basis for inference about mortality reduction across cancers potentially detectable by MCED tests.

IMPACT

Stage shift may be an appealing endpoint for evaluation of cancer screening tests but it appears to be an unreliable predictor of mortality benefit; furthermore, the same stage shift can mean different things for different cancers.

Early detection and treatment strategies for breast cancer in low-income and upper middle-income countries: a modelling study

BACKGROUND

Poor breast cancer survival in low-income and middle-income countries (LMICs) can be attributed to advanced-stage presentation and poor access to systemic therapy. We aimed to estimate the outcomes of different early detection strategies in combination with systemic chemotherapy and endocrine therapy in LMICs.

METHODS

We adapted a microsimulation model to project outcomes of three early detection strategies alone or in combination with three systemic treatment programmes beyond standard of care (programme A): programme B was endocrine therapy for all oestrogen-receptor (ER)-positive cases; programme C was programme B plus chemotherapy for ER-negative cases; programme D was programme C plus chemotherapy for advanced ER-positive cases. The main outcomes were reductions in breast cancer-related mortality and lives saved per 100 000 women relative to the standard of care for women aged 30-49 years in a low-income setting (East Africa; using incidence data and life tables from Uganda and data on tumour characteristics from various East African countries) and for women aged 50-69 years in a middle-income setting (Colombia).

FINDINGS

In the East African setting, relative mortality reductions were 8-41%, corresponding to 23 (95% uncertainty interval -12 to 49) to 114 (80 to 138) lives saved per 100 000 women over 10 years. In Colombia, mortality reductions were 7-25%, corresponding to 32 (-29 to 70) to 105 (61 to 141) lives saved per 100 000 women over 10 years.

INTERPRETATION

The best projected outcomes were in settings where access to both early detection and adjuvant therapy is improved. Even in the absence of mammographic screening, improvements in detection can provide substantial benefit in settings where advanced-stage presentation is common.

FUNDING

Fred Hutchinson Cancer Research Center/University of Washington Cancer Consortium Cancer Center Support Grant of the US National Institutes of Health.

The Effect of Treatment Advances on the Mortality Results of Breast Cancer Screening Trials: A Microsimulation Model

BACKGROUND

Mammography trials, which are the primary sources of evidence for screening benefit, were conducted decades ago. Whether advances in systemic therapies have rendered previously observed benefits of screening less significant is unknown.

OBJECTIVE

To compare the outcomes of breast cancer screening trials had they been conducted using contemporary systemic treatments with outcomes of trials conducted with previously used treatments.

DESIGN

Computer simulation model of 3 virtual screening trials with similar reductions in advanced-stage cancer cases but reflecting treatment patterns in 1975 (prechemotherapy era), 1999, or 2015 (treatment according to receptor status).

DATA SOURCES

Meta-analyses of screening and treatment trials; study of dissemination of primary systemic treatments; SEER (Surveillance, Epidemiology, and End Results) registry.

TARGET POPULATION

U.S. women aged 50 to 74 years.

TIME HORIZON

10 and 25 years.

PERSPECTIVE

Population.

INTERVENTION

Mammography, chemotherapy, tamoxifen, aromatase inhibitors, and trastuzumab.

OUTCOME MEASURES

Breast cancer mortality rate ratio (MRR) and absolute risk reduction (ARR) obtained by the difference in cumulative breast cancer mortality between control and screening groups.

RESULTS OF BASE-CASE ANALYSIS

At 10 years, screening in a 1975 trial yielded an MRR of 90% and an ARR of 5 deaths per 10,000 women. A 2015 screening trial yielded a 10-year MRR of 90% and an ARR of 3 deaths per 10,000 women.

RESULTS OF SENSITIVITY ANALYSIS

Greater reductions in advanced-stage disease yielded a greater screening effect, but MRRs remained similar across trials. However, ARRs were consistently lower under contemporary treatments. When contemporary treatments were available only for early-stage cases, the MRR was 88%.

LIMITATION

Disease models simplify reality and cannot capture all breast cancer subtypes.

CONCLUSION

Advances in systemic therapies for breast cancer have not substantively reduced the relative benefits of screening but have likely reduced the absolute benefits because of their positive effect on breast cancer survival.

PRIMARY FUNDING SOURCE

University of Washington and National Cancer Institute.

The epigenetic promise for prostate cancer diagnosis

BACKGROUND

Prostate cancer is the most common cancer diagnosis in men and a leading cause of death. Improvements in disease management would have a significant impact and could be facilitated by the development of biomarkers, whether for diagnostic, prognostic, or predictive purposes. The blood-based prostate biomarker PSA has been part of clinical practice for over two decades, although it is surrounded by controversy. While debates of usefulness are ongoing, alternatives should be explored. Particularly with recent recommendations against routine PSA-testing, the time is ripe to explore promising biomarkers to yield a more efficient and accurate screening for detection and management of prostate cancer. Epigenetic changes, more specifically DNA methylation, are amongst the most common alterations in human cancer. These changes are associated with transcriptional silencing of genes, leading to an altered cellular biology.

METHODS

One gene in particular, GSTP1, has been widely studied in prostate cancer. Therefore a meta-analysis has been conducted to examine the role of this and other genes and the potential contribution to prostate cancer management and screening refinement.

RESULTS

More than 30 independent, peer reviewed studies have reported a consistently high sensitivity and specificity of GSTP1 hypermethylation in prostatectomy or biopsy tissue. The meta-analysis combined and compared these results.

CONCLUSIONS

GSTP1 methylation detection can serve an important role in prostate cancer managment. The meta-analysis clearly confirmed a link between tissue DNA hypermethylation of this and other genes and prostate cancer. Detection of DNA methylation in genes, including GSTP1, could serve an important role in clinical practice.

The burden of prostate cancer in Asian nations

INTRODUCTION

In this review, the International Agency for Research on Cancer's cancer epidemiology databases were used to examine prostate cancer (PCa) age-standardized incidence rates (ASIR) in selected Asian nations, including Cancer Incidence in Five Continents (CI5) and GLOBOCAN databases, in an effort to determine whether ASIRs are rising in regions of the world with historically low risk of PCa development.

MATERIALS AND METHODS

Asian nations with adequate data quality were considered for this review. PCa ASIR estimates from CI5 and GLOBOCAN 2008 public use databases were examined in the four eligible countries: China, Japan, Korea and Singapore. Time trends in PCa ASIRs were examined using CI5 Volumes I-IX.

RESULTS

While PCa ASIRs remain much lower in the Asian nations examined than in North America, there is a clear trend of increasing PCa ASIRs in the four countries examined.

CONCLUSION

Efforts to systematically collect cancer incidence data in Asian nations must be expanded. Current CI5 data indicate a rise in PCa ASIR in several populous Asian countries. If these rates continue to rise, it is uncertain whether there will be sufficient resources in place, in terms of trained personnel and infrastructure for medical treatment and continuum of care, to handle the increase in PCa patient volume. The recommendation by some experts to initiate PSA screening in Asian nations could compound a resource shortfall. Obtaining accurate estimates of PCa incidence in these countries is critically important for preparing for a potential shift in the public health burden posed by this disease.

Declining death rates reflect progress against cancer

BACKGROUND

The success of the "war on cancer" initiated in 1971 continues to be debated, with trends in cancer mortality variably presented as evidence of progress or failure. We examined temporal trends in death rates from all-cancer and the 19 most common cancers in the United States from 1970-2006.

METHODOLOGY/PRINCIPAL FINDINGS

We analyzed trends in age-standardized death rates (per 100,000) for all cancers combined, the four most common cancers, and 15 other sites from 1970-2006 in the United States using joinpoint regression model. The age-standardized death rate for all-cancers combined in men increased from 249.3 in 1970 to 279.8 in 1990, and then decreased to 221.1 in 2006, yielding a net decline of 21% and 11% from the 1990 and 1970 rates, respectively. Similarly, the all-cancer death rate in women increased from 163.0 in 1970 to 175.3 in 1991 and then decreased to 153.7 in 2006, a net decline of 12% and 6% from the 1991 and 1970 rates, respectively. These decreases since 1990/91 translate to preventing of 561,400 cancer deaths in men and 205,700 deaths in women. The decrease in death rates from all-cancers involved all ages and racial/ethnic groups. Death rates decreased for 15 of the 19 cancer sites, including the four major cancers, with lung, colorectum and prostate cancers in men and breast and colorectum cancers in women.

CONCLUSIONS/SIGNIFICANCE

Progress in reducing cancer death rates is evident whether measured against baseline rates in 1970 or in 1990. The downturn in cancer death rates since 1990 result mostly from reductions in tobacco use, increased screening allowing early detection of several cancers, and modest to large improvements in treatment for specific cancers. Continued and increased investment in cancer prevention and control, access to high quality health care, and research could accelerate this progress.

Recent time trends in the epidemiology of stage IV prostate cancer in the United States: analysis of data from the Surveillance, Epidemiology, and End Results Program

OBJECTIVES

To describe recent epidemiologic trends in stage IV prostate cancer. Although advances in screening and diagnostic techniques have led to earlier detection of prostate cancer, a portion of patients still present with late-stage disease.

METHODS

Population-based cancer registry data from the Surveillance, Epidemiology, and End Results Program (cases from 1988 to 2003, follow-up through 2005) were used to calculate annual age-adjusted incidence rates of stage IV prostate cancer (overall and for the subset presenting with distant metastases) and to assess time trends in patient, tumor, and treatment characteristics and survival.

RESULTS

From 1988 to 2003, the age-adjusted incidence of stage IV prostate cancer significantly declined by 6.4% each year. The proportion of men diagnosed at younger ages, with poorly differentiated tumors, or who underwent a radical prostatectomy significantly increased over time. Five-year relative survival improved across the study period (from 41.6% to 62.3%), particularly in those diagnosed at younger ages or with moderately to well-differentiated tumors. Later years of diagnosis were independently associated with a decreased risk of death (from all causes and from prostate cancer specifically) after controlling for important patient, tumor, and treatment characteristics. Tumor grade and receipt of radical prostatectomy appeared to be the strongest independent prognostic indicators. Temporal trends were similar in the subset presenting with distant metastases, except that no significant improvement in survival was observed.

CONCLUSIONS

As younger men may expect to live longer with advanced prostate cancer, there remains a need to widen the range of therapeutic and supportive care options.

Cancer screenings, diagnostic technology evolution, and cancer control

Screening should allow for the anticipation of cancer diagnosis at an earlier stage, when curative treatment is possible. Screening for cervical, large bowel, and breast cancer were shown to be effective in reducing mortality. The wide acceptance of the screening concept led to the wide diffusion also of screening of uncertain benefit against prostate cancer and skin melanoma. Diagnostic technologies are continuously evolving, and new tests are proposed to improve existing screenings or as screening tests for additional cancer sites (e.g., lung cancer). Cancer screening, however, is a complex and costly intervention that does not result only in benefits but also may cause harm. A major emerging problem of screening is overdiagnosis, or the detection of cases that would have not progressed to the symptomatic phase in the absence of screening. Thus, both experimental and observational evaluation studies are needed to reduce harm caused by screenings and to select effective interventions among many proposed innovations. Finally, the research of markers to assess the aggressive nature of screen-detected lesions is of great importance to improve screenings ' harm/benefit ratio.

Impact of PSA screening on the incidence of advanced stage prostate cancer in the United States: a surveillance modeling approach

BACKGROUND

and objective. Both the detection and the treatment of prostate cancer have undergone important clinical advances. Simultaneously, both distant stage incidence and disease-specific mortality have fallen in the United States. A recent study suggests that if prostate-specific antigen (PSA) testing explains the decline in distant stage incidence, then it may be largely responsible for the decline in mortality. The objective was to quantify this link between PSA screening and the decline in distant stage incidence.

METHODS

A fixed-cohort simulation model of prostate cancer progression and screening was adapted to a population-based model that integrates new data on trends in testing and biopsy practices. The model was calibrated to pre-PSA incidence and then screening was superimposed, obtaining incidence projections in the absence and presence of testing. This approach permits calculation of clinically relevant measures for model validation and direct assessment of the role of testing in the distant stage incidence decline.

RESULTS

The model validated well with prior studies of natural history, and the sensitivity analysis indicated that the findings were robust to variation in model parameters. Model results indicate that PSA screening accounts for approximately 80% of the observed decline in distant stage incidence.

CONCLUSIONS

PSA screening contributed to the observed declines in distant stage incidence and mortality in the 1990s. However, additional factors, such as increasing awareness of prostate cancer and advances in treatment, have probably also played a role in these trends.

Reconstructing PSA testing patterns between black and white men in the US from Medicare claims and the National Health Interview Survey

BACKGROUND

Frequencies of prostate-specific antigen (PSA) test administration were not actively monitored on a national level during the first decade of PSA testing. The objectives of this article were to reconstruct patterns of PSA testing between black and white men in the US and to determine the extent of any racial disparity in PSA use.

METHODS

Data from the 2000 National Health Interview Survey were used to model the adoption of PSA and to estimate the distribution of age at first test. Longitudinal Medicare claims data were used to estimate the distribution of intervals between tests. The rates of initial and subsequent tests were then combined by simulation to reconstruct individual screening histories. Results are from the reconstructed model.

RESULTS

Overall, 45% of white men and 43% of black men within ages 40-84 years had at least 1 PSA test by the year 2000. The authors found that among older men, whites adopted PSA screening earlier than blacks, whereas among younger men, this trend was reversed, with blacks adopting screening earlier than whites. Annual testing frequencies generated by the simulation model were higher for white men aged>or=60 years and higher for black men aged<60 years.

CONCLUSIONS

Findings indicated fairly similar patterns overall of PSA testing for blacks and whites. These similarities indicated that racial disparity in PSA testing is probably not a major factor behind current racial differences in prostate cancer mortality rates and declines. Knowledge of patterns of screening is important to an understanding of the impact of population screening on cancer incidence and mortality, but retrospective data sources have significant limitations when used to estimate these patterns of care.

Overall survival in the intervention arm of a randomized controlled screening trial for prostate cancer compared with a clinically diagnosed cohort

OBJECTIVES

This population-based study provides comparisons of prostate cancer characteristics at diagnosis of two cohorts of men from two well-defined geographical areas exposed to different intensities of prostate cancer screening. Overall survival in both cohorts was compared with that in the general population.

METHODS

A cohort of 822 men randomized to the intervention arm of a prostate cancer screening trial and subsequently diagnosed with prostate cancer was compared with a nonrandomized cohort of 947 men who were clinically diagnosed with prostate cancer in a geographically neighboring region. In both cohorts, cases were diagnosed with prostate cancer between January 1989 and December 1997. A partitioning of overall survival by variables associated with cancer onset such as age at diagnosis, stage at diagnosis, and grade at diagnosis was performed.

RESULTS

Age at diagnosis, tumor extent at diagnosis, and grade at diagnosis were significantly different between the screened and clinically diagnosed cohort. The 5- and 10-yr survival rates were higher in the screened cohort than in the clinically diagnosed cohort (88.8% vs. 52.4%, and 68.4% vs. 29.6%, respectively). Significant differences in survival were evident for all age, stage, and grade subgroups, except for metastatic disease at diagnosis.

CONCLUSIONS

Differences in overall survival favoring the screened population were observed for all baseline characteristics (age, stage, and grade of disease), and these variables may all explain differences in overall survival because screening achieves early diagnosis as well as a stage and grade shift. As observed survival rates in the screened population mirrored those within the general population, the contribution of lead time and overdiagnosis to final patient outcome is considered to be large as well.

The changing age distribution of prostate cancer in Canada

BACKGROUND

Prostate cancer incidence rates are still increasing steadily; mortality rates are levelling, possibly decreasing; and hospitalization rates for many diagnoses are decreasing. Our objective is to examine changes in age distributions of prostate cancer during these times of change.

METHODS

Prostate cancer cases were derived from the Canadian Cancer Registry, prostate cancer deaths from Vital Statistics, hospitalizations from the Hospital Morbidity File. Age-standardized rates were calculated based on the 1991 Canadian population. A prevalence correction for incidence rates was calculated.

RESULTS

Age-specific incidence rates increased until 1995 for all ages, but a superimposed peak (1991-94) was greatest between ages 60-79. After 1995, increases in incidence continued for the under-70 age groups. Prevalence correction indicated the greatest underestimation of incidence rates for the oldest ages, but was less in Canada than in the United States. Mortality rates increased until 1994, then levelled and slowly decreased; age-specific mortality rates showed the greatest increase for the oldest ages but the earliest downturn for younger age groups. While hospitalizations dropped drastically after 1991, this drop was confined to elderly men (70+).

CONCLUSIONS

Dramatic changes in age distributions of prostate cancer incidence, mortality and hospitalizations altered age profiles of men with prostate cancer. This illustrated the changing nature of prostate cancer as a public health issue and has important implications for health care provision, e.g., the increased numbers of younger new patients have different needs from the increasing numbers of elderly long-term patients who now spend less time in hospital.

Assessing the impact of prescribed medicines on health outcomes

This paper reviews methods that can be used to assess the impact of medicine use on population health outcomes. In the absence of a gold standard, we argue that a convergence of evidence from different types of studies using multiple methods of independent imperfection provides the best bases for attributing improvements in health outcomes to the use of medicines. The major requirements are: good evidence that a safe and effective medicine is being appropriately prescribed; covariation between medicine use and improved health outcomes; and being able to discount alternative explanations of the covariation (via covariate adjustment, propensity analyses and sensitivity analyses), so that medicine use is the most plausible explanation of the improved health outcomes. The strongest possible evidence would be provided by the coherence of the following types of evidence: (1) individual linked data showing that patients are prescribed the medicine, there are reasonable levels of patient compliance, and there is a relationship between medicine use and health improvements that is not explained by other factors; (2) ecological evidence of improvements in these health outcomes in the population in which the medicine is used. Confidence in these inferences would be increased by: the replication of these results in comparable countries and consistent trends in population vital statistics in countries that have introduced the medicine; and epidemiological modelling indicating that changes observed in population health outcomes are plausible given the epidemiology of the condition being treated.

The interpretation of serum prostate specific antigen in men receiving 5alpha-reductase inhibitors: a review and clinical recommendations

PURPOSE

We reviewed the effects of 5alpha-reductase inhibitors on prostate specific antigen and clarified the adjustments that should be made to compensate for these effects to ensure that the usefulness of prostate specific antigen for detecting prostate cancer is maintained.

MATERIALS AND METHODS

We reviewed articles published in the scientific literature with relevance to the effects of 5alpha-reductase inhibitors on the usefulness of prostate specific antigen for detecting prostate cancer.

RESULTS

A total serum prostate specific antigen of 4.0 ng/ml has traditionally been used as the threshold for triggering prostate biopsy. However, clinical trials of finasteride and dutasteride have shown that 5alpha-reductase inhibitors decrease serum prostate specific antigen in patients with and without prostate cancer. To compensate, the doubling rule has been applied in clinical trials and clinical practice. However, doubling serum prostate specific antigen may overestimate actual prostate specific antigen in some patients receiving 5alpha-reductase inhibitors for up to 6 to 9 months, accurately estimate prostate specific antigen from 1 to 3 years and underestimate it thereafter. An increase in prostate specific antigen of 0.3 ng/ml from nadir as a trigger for biopsy maintains 71% sensitivity for prostate cancer in men receiving dutasteride with 60% specificity, similar to the 4.0 ng/ml prostate specific antigen cutoff using placebo.

CONCLUSIONS

We propose that a prostate specific antigen increase from nadir of 0.3 ng/ml or greater could represent an alternative to the doubling rule for monitoring prostate specific antigen in patients on 5alpha-reductase inhibitors. The prostate specific antigen increase from nadir appears to be a more accurate cancer indicator than a doubled value in some patients.

Trends in prostate cancer incidence, hospital utilization and surgical procedures, Canada, 1981-2000

BACKGROUND

Numbers of new prostate cancer cases in Canada continue to increase because of increasing prostate cancer incidence, population growth, aging of the population, and earlier detection methods such as PSA (prostate-specific antigen) testing. Concern has been expressed that PSA-related increases in incidence will make unaffordable demands on Canadian hospital resources. Our objective is to relate increases in prostate cancer incidence to trends in hospitalizations and in- patient treatment.

METHODS

Hospitalizations with prostate cancer as primary diagnosis were obtained from the Hospital Morbidity Database, estimates of prostate cancer day surgery from the Discharge Abstract Database, newly diagnosed cases from the Canadian Cancer Registry, and prostate cancer deaths from the Vital Statistics Mortality Databases--all for the years 1981-2000.

RESULTS

Between 1981-2000, the number of new cases rose from 7,000 to 18,500 with a transient peak, 1991-1994. Hospitalizations rose parallel to the incidence until 1991 but then fell sharply in spite of further increasing incidence. The use of radical prostatectomy (RP) increased steadily, but transurethral prostatectomy and bilateral orchiectomy decreased in the 1990s. Decreases in length of stay and in number of hospitalizations resulted in considerably decreased annual hospital days for all prostate cancer in-patient procedures except RP, which remained level since 1993.

CONCLUSIONS

A net decrease in number of in-patient days occurred, despite the increasing number of new prostate cancer cases and the increasing use of radical prostatectomy. We concluded that increases in hospital utilization due to early detection programs, such as PSA testing, are unlikely to overwhelm in-patient services of Canadian hospitals.

The use of modeling to understand the impact of screening on U.S. mortality: examples from mammography and PSA testing

Surveillance data represent a vital resource for understanding the impact of cancer control interventions on the population cancer burden. However, population cancer trends are a complex product of many factors, and estimating the contribution of any one of these factors can be challenging. Surveillance modeling is a technique for estimating the contribution of one or more interventions of interest to trends in disease incidence and mortality. In this article, we present several approaches to surveillance modeling of cancer screening interventions. We classify models as biological or epidemiological, depending on whether they model the full unobservable aspects of disease onset and progression, or models which reduce the complex process to simpler terms by summarizing portions of the disease process using mostly observed population level measures. We also describe differences between macrolevel models, microsimulation models and mechanistic models. We discuss procedures for model calibration and validation, and methods for presenting model results which are robust with respect to certain types of biased model estimates. As examples, we present several models of the impact of mammography screening on breast cancer mortality, and PSA screening on prostate cancer mortality. Both these examples are appropriate uses of surveillance modeling, even though for mammography there is extensive (although somewhat controversial) randomized trial evidence, whereas for PSA this biomarker has seen extensive use as a screening test prior to any controlled trial evidence of its efficacy. Some of the models presented here were developed as part of the National Cancer Institute's Cancer Intervention and Surveillance Modeling Network.

The science of early detection

Most clinical judgment and clinical intuition derives from observations made on patients who suffer from a disease or medical condition. However, the target population for cancer screening is healthy people who would not seek out a health professional unless convinced to do so by advertising or public messages. Extrapolation of clinical observations to the target population for screening can be very misleading and even harmful. This is because powerful screening biases and confounding effects--such as selection bias, lead-time bias, length-bias sampling, and overdiagnosis--can mislead even the most astute clinician. This article will discuss those biases, review methods to avoid them, and provide useful resources to the clinician or health scientist.

Late toxicity following conventional radiotherapy for prostate cancer: analysis of the EORTC trial 22863

Late toxicity and other serious adverse events (SAE) were analysed in the European Organisation for Research and Treatment of Cancer (EORTC) trial 22863. The study evaluated the value of adjuvant endocrine treatment for locally advanced prostate cancer treated with radiotherapy. From 1987 to 1995, 415 patients were randomised. There was long-term toxicity information for 377 patients (91%). Median age was 70 years (range 50-80 years). Median follow-up for late toxicity was 42 months (range 3-136 months). Toxicity was graded according to a modified Radiotherapy and Oncology Group (RTOG) scale. Other late SAE, that was not classified as severe treatment toxicity, but were still life-threatening, were also assessed. There were 72 patients with grade 2, 10 patients with grade 3 and 4 patients with grade 4 toxicity. There were 20 patients with other late SAE, who were grouped according to their relationship to treatment; likely related (n = 1), unrelated (n = 7) and not assessable (n = 12). Although four treatment-related deaths (1%) occurred, grade 3 or 4 late complications were less than 5%.

Prostate carcinoma presentation, diagnosis, and staging: an update form the National Cancer Data Base

BACKGROUND

Based on the 1998 Patient Care Evaluation (PCE) from the American College of Surgeons National Cancer Data Base (NCDB), the authors described contemporary nationwide patterns of prostate carcinoma presentation, diagnosis, and staging.

METHODS

The authors reviewed 54,212 cases from the 1998 PCE. Demographics, presenting signs and symptoms, tumor characteristics, prostate biopsy techniques, and use of staging modalities were evaluated.

RESULTS

The mean age of patients in the sample was 68 years. Among patients with available data, 87.5% had a prostate specific antigen (PSA) level of 4 ng/mL or higher, 83.1% had American Joint Committee on Cancer (AJCC) Stage I-II lesions, 80.2% had well or moderately differentiated cancers, and 68.7% of newly diagnosed patients were asymptomatic. Compared with symptomatic patients, asymptomatic patients were more likely to have localized disease (84.6% vs. 78.2%, P < 0.01) and well or moderately differentiated tumors (82.2% vs. 74.6%, P < 0.01). Transrectal ultrasound-guided prostate biopsy was the most common method of tissue confirmation (45.4%). Radionuclide bone scintigraphy was the most frequently employed staging modality (48.7%). Use of various staging evaluations was more frequent among patients at increased risk for disseminated disease (PSA > 10 ng/mL and/or high-grade tumors) versus patients at lower risk (PSA < or = 10 and low to moderate-grade tumors) for metastatic disease (P < 0.005).

CONCLUSIONS

Most newly diagnosed patients with prostate carcinoma are asymptomatic and have moderately differentiated and organ-confined disease. Compared with symptomatic patients, tumors in asymptomatic men are associated with lower pretreatment PSA levels, AJCC stage, and tumor grade. Selective use of staging evaluations, based on risk of metastatic disease, may be relatively uncommon. The NCDB remains a unique and rich source of novel patient care information and serves as a national point of reference for prostate carcinoma presentation, diagnosis, and staging.

The case for early detection

Early detection represents one of the most promising approaches to reducing the growing cancer burden. It already has a key role in the management of cervical and breast cancer, and is likely to become more important in the control of colorectal, prostate and lung cancer. Early-detection research has recently been revitalized by the advent of novel molecular technologies that can identify cellular changes at the level of the genome or proteome, but how can we harness these new technologies to develop effective and practical screening tests?