An efficient strategy for evaluating new non-invasive screening tests for colorectal cancer: the guiding principles

OBJECTIVE

New screening tests for colorectal cancer (CRC) are rapidly emerging. Conducting trials with mortality reduction as the end point supporting their adoption is challenging. We re-examined the principles underlying evaluation of new non-invasive tests in view of technological developments and identification of new biomarkers.

DESIGN

A formal consensus approach involving a multidisciplinary expert panel revised eight previously established principles.

RESULTS

Twelve newly stated principles emerged. Effectiveness of a new test can be evaluated by comparison with a proven comparator non-invasive test. The faecal immunochemical test is now considered the appropriate comparator, while colonoscopy remains the diagnostic standard. For a new test to be able to meet differing screening goals and regulatory requirements, flexibility to adjust its positivity threshold is desirable. A rigorous and efficient four-phased approach is proposed, commencing with small studies assessing the test's ability to discriminate between CRC and non-cancer states (phase I), followed by prospective estimation of accuracy across the continuum of neoplastic lesions in neoplasia-enriched populations (phase II). If these show promise, a provisional test positivity threshold is set before evaluation in typical screening populations. Phase III prospective studies determine single round intention-to-screen programme outcomes and confirm the test positivity threshold. Phase IV studies involve evaluation over repeated screening rounds with monitoring for missed lesions. Phases III and IV findings will provide the real-world data required to model test impact on CRC mortality and incidence.

CONCLUSION

New non-invasive tests can be efficiently evaluated by a rigorous phased comparative approach, generating data from unbiased populations that inform predictions of their health impact.

In adults, a single colonoscopy screening invitation vs. no invitation reduced CRC incidence at 10 y

SOURCE CITATION

Bretthauer M, Løberg M, Wieszczy P, et al. Effect of colonoscopy screening on risks of colorectal cancer and related death. N Engl J Med. 2022;387:1547-56. 36214590.

In adults, sigmoidoscopy screening invitation reduced CRC incidence and related mortality at 15 y

Juul FE, Cross AJ, Schoen RE, et al. 15-year benefits of sigmoidoscopy screening on colorectal cancer incidence and mortality: a pooled analysis of randomized trials. Ann Intern Med. 2022;175:1525-33. 36215714.

Counting Advanced Precancerous Lesions as True Positives When Determining Colorectal Cancer Screening Test Specificity

The landmark Centers for Medicare & Medicaid Services (CMS) decision memo on blood-based biomarkers to screen for colorectal cancer (CRC) sets thresholds of 74% or higher for sensitivity and 90% or higher for specificity for CRC. This approach does not consider detection of advanced precancerous lesions as true positives. We contrasted the impact of counting advanced precancerous lesions as true vs false positives and projected CRC outcomes under contrasting tests in a validated model. A test with the threshold performance set by CMS decreased CRC incidence by 30% and CRC mortality by 48% in individuals aged 45 years. If this test also detected advanced precancerous lesions with 30% sensitivity, CRC incidence decreased by 45% and mortality by 58%, but the CRC specificity of the test of only 88% would not satisfy the CMS threshold. CMS should reconsider its definition of threshold specificity for CRC screening biomarkers. Future coverage determinations on biomarkers to screen for cancer should consider detection of relevant precursor lesions and projected outcomes.

Derivation and validation of a predictive model for advanced colorectal neoplasia in asymptomatic adults

OBJECTIVE

Knowing risk for advanced colorectal neoplasia (AN) could help patients and providers choose among screening tests, improving screening efficiency and uptake. We created a risk prediction model for AN to help decide which test might be preferred, a use not considered for existing models.

DESIGN

Average-risk 50-to-80-year olds undergoing first-time screening colonoscopy were recruited from endoscopy units in Indiana. We measured sociodemographic and physical features, medical and family history and lifestyle factors and linked these to the most advanced finding. We derived a risk equation on two-thirds of the sample and assigned points to each variable to create a risk score. Scores with comparable risks were collapsed into risk categories. The model and score were tested on the remaining sample.

RESULTS

Among 3025 subjects in the derivation set (mean age 57.3 (6.5) years; 52% women), AN prevalence was 9.4%. The 13-variable model (c-statistic=0.77) produced three risk groups with AN risks of 1.5% (95% CI 0.72% to 2.74%), 7.06% (CI 5.89% to 8.38%) and 27.26% (CI 23.47% to 31.30%) in low-risk, intermediate-risk and high-risk groups (p value <0.001), containing 23%, 59% and 18% of subjects, respectively. In the validation set of 1475 subjects (AN prevalence of 8.4%), model performance was comparable (c-statistic=0.78), with AN risks of 2.73% (CI 1.25% to 5.11%), 5.57% (CI 4.12% to 7.34%) and 25.79% (CI 20.51% to 31.66%) in low-risk, intermediate-risk and high-risk subgroups, respectively (p<0.001), containing proportions of 23%, 59% and 18%.

CONCLUSION

Among average-risk persons, this model estimates AN risk with high discrimination, identifying a lower risk subgroup that may be screened non-invasively and a higher risk subgroup for which colonoscopy may be preferred. The model could help guide patient-provider discussions of screening options, may increase screening adherence and conserve colonoscopy resources.

Mortality From Postscreening (Interval) Colorectal Cancers Is Comparable to That From Cancer in Unscreened Patients-A Randomized Sigmoidoscopy Trial

BACKGROUND & AIMS

Endoscopic screening for colorectal cancer (CRC) is performed at longer time intervals than the fecal occult blood test or screenings for breast or prostate cancer. This causes concerns about interval cancers, which have been proposed to progress more rapidly. We compared outcomes of patients with interval CRCs after sigmoidoscopy screening vs outcomes of patients with CRC who had not been screened.

METHODS

We performed a secondary analysis of a randomized sigmoidoscopy screening trial in Norway with 98,684 participants (age range, 50-64 years) who were randomly assigned to groups that were (n = 20,552) or were not (n = 78,126) invited for sigmoidoscopy screening from 1999 through 2001; participants were followed up for a median 14.8 years. We compared CRC mortality and all-cause mortality between individuals who underwent screening and were diagnosed with CRC 30 days or longer after screening (interval cancer group, n = 163) and individuals diagnosed with CRC in the nonscreened group (controls, n = 1740). All CRCs in the control group were identified when they developed symptoms (clinically detected CRCs). Analyses were stratified by cancer site. We used Cox regression to estimate hazard ratio (HRs), adjusted for age and sex.

RESULTS

Over the follow-up period, 43 individuals in the interval cancer group died from CRC; among controls, 525 died from CRC. CRC mortality (adjusted HR, 0.98; 95% confidence interval, 0.72-1.35; P = .92), rectosigmoid cancer mortality (adjusted HR, 1.10; 95% confidence interval, 0.63-1.92; P = .74), and all-cause mortality (adjusted HR, 0.99; 95% confidence interval, 0.76-1.27; P = .91) did not differ significantly between the interval cancer group and controls.

CONCLUSIONS

In this randomized sigmoidoscopy screening trial, mortality did not differ significantly between individuals with interval CRCs and unscreened patients with clinically detected CRCs. ClinicalTrials.gov identifier: NCT00119912.

Institutional Responsibility and the Flawed Genomic Biomarkers at Duke University: A Missed Opportunity for Transparency and Accountability

When there have been substantial failures by institutional leadership in their oversight responsibility to protect research integrity, the public should demand that these be recognized and addressed by the institution itself, or the funding bodies. This commentary discusses a case of research failures in developing genomic predictors for cancer risk assessment and treatment at a leading university. In its review of this case, the Office of Research Integrity, an agency within the US Department of Health and Human Services, focused their report entirely on one individual faculty member and made no comment on the institution's responsibility and its failure to provide adequate oversight and investigation. These actions missed an important opportunity to emphasize the institution's critical responsibilities in oversight of research integrity and the importance of institutional transparency and accountability.

Abstract IA07: Using genetic information in screening and prevention: Perspective of clinicians and policy-makers

How can genetic information be effectively used in screening and prevention?

The conceptual framework and rules of evidence for answering this question - widely used by clinicians, policy-makers, and payors - has been developed over decades in the field of Evidence-Based Medicine, exemplified by the approach of the USPSTF (US Preventive Services Task Force) and EGAPP (Evaluation of Genomic Applications in Practice and Prevention). The framework's principles include using the best evidence (clinical trials where available, and observational data where necessary) assessed in systematic searches that consider quality of each study using specific rules of evidence. Outcomes are projected quantitatively to assess net benefit (benefits vs harms) of prevention and screening strategies.

In this framework, genetic data may provide information about the magnitude of lifetime risk of developing a specific cancer, while other data (including genomic data) may provide information about the current risk that a cancer is present. Risks of appropriate magnitude may direct interventions that can prevent cancer (for example chemoprevention or preventive surgery) or that can detect the presence of early curable cancer or an important precursor.

This talk will describe the quantitative conceptual framework and its rationale, along with the implications, challenges, and opportunities for the use of genetic and genomic information for cancer prevention and screening.

Citation Format: David F. Ransohoff. Using genetic information in screening and prevention: Perspective of clinicians and policy-makers. [abstract]. In: Proceedings of the AACR Special Conference: Improving Cancer Risk Prediction for Prevention and Early Detection; Nov 16-19, 2016; Orlando, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2017;26(5 Suppl):Abstract nr IA07.

Risk of Advanced Neoplasia Using the National Cancer Institute's Colorectal Cancer Risk Assessment Tool

Background

There is no validated, discriminating, and easy-to-apply tool for estimating risk of colorectal neoplasia. We studied whether the National Cancer Institute's (NCI's) Colorectal Cancer (CRC) Risk Assessment Tool, which estimates future CRC risk, could estimate current risk for advanced colorectal neoplasia among average-risk persons.

Methods

This cross-sectional study involved individuals age 50 to 80 years undergoing first-time screening colonoscopy. We measured medical and family history, lifestyle information, and physical measures and calculated each person's future CRC risk using the NCI tool's logistic regression equation. We related quintiles of future CRC risk to the current risk of advanced neoplasia (sessile serrated polyp or tubular adenoma ≥ 1 cm, a polyp with villous histology or high-grade dysplasia, or CRC). All statistical tests were two-sided.

Results

For 4457 (98.5%) with complete data (mean age = 57.2 years, SD = 6.6 years, 51.7% women), advanced neoplasia prevalence was 8.26%. Based on quintiles of five-year estimated absolute CRC risk, current risks of advanced neoplasia were 2.1% (95% confidence interval [CI] = 1.3% to 3.3%), 4.8% (95% CI = 3.5% to 6.4%), 6.4% (95% CI = 4.9% to 8.2%), 10.0% (95% CI = 8.1% to 12.1%), and 17.6% (95% CI = 15.5% to 20.6%; P < .001). For quintiles of estimated 10-year CRC risk, corresponding current risks for advanced neoplasia were 2.2% (95% CI = 1.4% to 3.5%), 4.8% (95% CI = 3.5% to 6.4%), 6.5% (95% CI = 5.0% to 8.3%), 9.3% (95% CI = 7.5% to 11.4%), and 18.4% (95% CI = 15.9% to 21.1%; P < .001). Among persons with an estimated five-year CRC risk above the median, current risk for advanced neoplasia was 12.8%, compared with 3.7% among those below the median (relative risk = 3.4, 95 CI = 2.7 to 4.4).

Conclusions

The NCI's Risk Assessment Tool, which estimates future CRC risk, may be used to estimate current risk for advanced neoplasia, making it potentially useful for tailoring and improving CRC screening efficiency among average-risk persons.

Derivation and Validation of a Scoring System to Stratify Risk for Advanced Colorectal Neoplasia in Asymptomatic Adults: A Cross-sectional Study

BACKGROUND

Several methods are recommended equally strongly for colorectal cancer screening in average-risk persons. Risk stratification would enable tailoring of screening within this group, with less invasive tests (sigmoidoscopy or occult blood tests) for lower-risk persons and colonoscopy for higher-risk persons.

OBJECTIVE

To create a risk index for advanced neoplasia (colorectal cancer and adenomas or serrated polyps ≥1.0 cm, villous histology, or high-grade dysplasia) anywhere in the colorectum, using the most common risk factors for colorectal neoplasia.

DESIGN

Cross-sectional study.

SETTING

Multiple endoscopy units, primarily in the Midwest.

PATIENTS

Persons aged 50 to 80 years undergoing initial screening colonoscopy (December 2004 to September 2011).

MEASUREMENTS

Derivation and validation of a risk index based on points from regression coefficients for age, sex, waist circumference, cigarette smoking, and family history of colorectal cancer.

RESULTS

Among 2993 persons in the derivation set, prevalence of advanced neoplasia was 9.4%. Risks for advanced neoplasia in persons at very low, low, intermediate, and high risk were 1.92% (95% CI, 0.63% to 4.43%), 4.88% (CI, 3.79% to 6.18%), 9.93% (CI, 8.09% to 12.0%), and 24.9% (CI, 21.1% to 29.1%), respectively (P < 0.001). Sigmoidoscopy to the descending colon in the low-risk groups would have detected 51 of 70 (73% [CI, 61% to 83%]) advanced neoplasms. Among 1467 persons in the validation set, corresponding risks for advanced neoplasia were 1.65% (CI, 0.20% to 5.84%), 3.31% (CI, 2.08% to 4.97%), 10.9% (CI, 8.26% to 14.1%), and 22.3% (CI, 16.9% to 28.5%), respectively (P < 0.001). Sigmoidoscopy would have detected 21 of 24 (87.5% [CI, 68% to 97%]) advanced neoplasms.

LIMITATIONS

Split-sample validation; results apply to first-time screening.

CONCLUSION

This index stratifies risk for advanced neoplasia among average-risk persons by identifying lower-risk groups for which noncolonoscopy strategies may be effective and efficient and a higher-risk group for which colonoscopy may be preferred.

PRIMARY FUNDING SOURCE

National Cancer Institute, Walther Cancer Institute, Indiana University Simon Cancer Center, and Indiana Clinical and Translational Sciences Institute.

Leveraging biospecimen resources for discovery or validation of markers for early cancer detection

Validation of early detection cancer biomarkers has proven to be disappointing when initial promising claims have often not been reproducible in diagnostic samples or did not extend to prediagnostic samples. The previously reported lack of rigorous internal validity (systematic differences between compared groups) and external validity (lack of generalizability beyond compared groups) may be effectively addressed by utilizing blood specimens and data collected within well-conducted cohort studies. Cohort studies with prediagnostic specimens (eg, blood specimens collected prior to development of clinical symptoms) and clinical data have recently been used to assess the validity of some early detection biomarkers. With this background, the Division of Cancer Control and Population Sciences (DCCPS) and the Division of Cancer Prevention (DCP) of the National Cancer Institute (NCI) held a joint workshop in August 2013. The goal was to advance early detection cancer research by considering how the infrastructure of cohort studies that already exist or are being developed might be leveraged to include appropriate blood specimens, including prediagnostic specimens, ideally collected at periodic intervals, along with clinical data about symptom status and cancer diagnosis. Three overarching recommendations emerged from the discussions: 1) facilitate sharing of existing specimens and data, 2) encourage collaboration among scientists developing biomarkers and those conducting observational cohort studies or managing healthcare systems with cohorts followed over time, and 3) conduct pilot projects that identify and address key logistic and feasibility issues regarding how appropriate specimens and clinical data might be collected at reasonable effort and cost within existing or future cohorts.

Transparent Reporting of a multivariable prediction model for Individual Prognosis or Diagnosis (TRIPOD): explanation and elaboration

The TRIPOD (Transparent Reporting of a multivariable prediction model for Individual Prognosis Or Diagnosis) Statement includes a 22-item checklist, which aims to improve the reporting of studies developing, validating, or updating a prediction model, whether for diagnostic or prognostic purposes. The TRIPOD Statement aims to improve the transparency of the reporting of a prediction model study regardless of the study methods used. This explanation and elaboration document describes the rationale; clarifies the meaning of each item; and discusses why transparent reporting is important, with a view to assessing risk of bias and clinical usefulness of the prediction model. Each checklist item of the TRIPOD Statement is explained in detail and accompanied by published examples of good reporting. The document also provides a valuable reference of issues to consider when designing, conducting, and analyzing prediction model studies. To aid the editorial process and help peer reviewers and, ultimately, readers and systematic reviewers of prediction model studies, it is recommended that authors include a completed checklist in their submission. The TRIPOD checklist can also be downloaded from www.tripod-statement.org.

Endoscopic detection of proximal serrated lesions and pathologic identification of sessile serrated adenomas/polyps vary on the basis of center

BACKGROUND & AIMS

We investigated rates of detection of proximal serrated lesions in a cohort of average-risk patients undergoing screening colonoscopies.

METHODS

We reviewed results from screening colonoscopies performed by attending gastroenterologists at 32 endoscopy centers from 2008-2010. Pathology slides were interpreted at the individual centers. For this analysis, serrated lesions included hyperplastic polyps larger than 10 mm, those interpreted as sessile serrated adenomas (or sessile serrated polyp), and traditional serrated adenomas. Rates of detection for conventional adenomas and serrated lesions were compared among centers.

RESULTS

A total of 5778 lesions were detected in 7215 screening colonoscopies. Of the 5548 lesions with pathology results, 3008 (54.2%) were conventional adenomas, 350 (6.3%) were serrated, and 232 (4.2%) were proximal serrated. The proportion of colonoscopies with at least 1 proximal serrated lesion was 2.8% (range among centers, 0%-9.8%). The number of serrated lesions per colonoscopy ranged from 0.00-0.11 (average, 0.05 ± 0.25). Overall lesion detection rates correlated with proximal serrated lesion detection rates (R = 0.91, P < .0001); conventional adenoma and proximal serrated lesion detection rates also correlated (R = .43, P = .025). The detection rate of proximal serrated lesions differed significantly among centers (P < .0001); odds ratios for detection ranged from 0-0.79. Some centers' pathologists never identified proximal serrated lesions as sessile serrated adenomas/polyps.

CONCLUSIONS

In an average-risk screening cohort, detection of proximal serrated lesions varied greatly among endoscopy centers. There was also substantial variation among pathologists in identification of sessile serrated adenomas/polyps. Nationally, a significant proportion of proximal serrated lesions may be missed during colonoscopy examination or incorrectly identified during pathology assessment. ClinicalTrials.gov Number: NCT00855348.

Addressing overdiagnosis and overtreatment in cancer: a prescription for change

A vast range of disorders--from indolent to fast-growing lesions--are labelled as cancer. Therefore, we believe that several changes should be made to the approach to cancer screening and care, such as use of new terminology for indolent and precancerous disorders. We propose the term indolent lesion of epithelial origin, or IDLE, for those lesions (currently labelled as cancers) and their precursors that are unlikely to cause harm if they are left untreated. Furthermore, precursors of cancer or high-risk disorders should not have the term cancer in them. The rationale for this change in approach is that indolent lesions with low malignant potential are common, and screening brings indolent lesions and their precursors to clinical attention, which leads to overdiagnosis and, if unrecognised, possible overtreatment. To minimise that potential, new strategies should be adopted to better define and manage IDLEs. Screening guidelines should be revised to lower the chance of detection of minimal-risk IDLEs and inconsequential cancers with the same energy traditionally used to increase the sensitivity of screening tests. Changing the terminology for some of the lesions currently referred to as cancer will allow physicians to shift medicolegal notions and perceived risk to reflect the evolving understanding of biology, be more judicious about when a biopsy should be done, and organise studies and registries that offer observation or less invasive approaches for indolent disease. Emphasis on avoidance of harm while assuring benefit will improve screening and treatment of patients and will be equally effective in the prevention of death from cancer.

Multitarget stool DNA testing for colorectal-cancer screening

BACKGROUND

An accurate, noninvasive test could improve the effectiveness of colorectal-cancer screening.

METHODS

We compared a noninvasive, multitarget stool DNA test with a fecal immunochemical test (FIT) in persons at average risk for colorectal cancer. The DNA test includes quantitative molecular assays for KRAS mutations, aberrant NDRG4 and BMP3 methylation, and β-actin, plus a hemoglobin immunoassay. Results were generated with the use of a logistic-regression algorithm, with values of 183 or more considered to be positive. FIT values of more than 100 ng of hemoglobin per milliliter of buffer were considered to be positive. Tests were processed independently of colonoscopic findings.

RESULTS

Of the 9989 participants who could be evaluated, 65 (0.7%) had colorectal cancer and 757 (7.6%) had advanced precancerous lesions (advanced adenomas or sessile serrated polyps measuring ≥1 cm in the greatest dimension) on colonoscopy. The sensitivity for detecting colorectal cancer was 92.3% with DNA testing and 73.8% with FIT (P=0.002). The sensitivity for detecting advanced precancerous lesions was 42.4% with DNA testing and 23.8% with FIT (P<0.001). The rate of detection of polyps with high-grade dysplasia was 69.2% with DNA testing and 46.2% with FIT (P=0.004); the rates of detection of serrated sessile polyps measuring 1 cm or more were 42.4% and 5.1%, respectively (P<0.001). Specificities with DNA testing and FIT were 86.6% and 94.9%, respectively, among participants with nonadvanced or negative findings (P<0.001) and 89.8% and 96.4%, respectively, among those with negative results on colonoscopy (P<0.001). The numbers of persons who would need to be screened to detect one cancer were 154 with colonoscopy, 166 with DNA testing, and 208 with FIT.

CONCLUSIONS

In asymptomatic persons at average risk for colorectal cancer, multitarget stool DNA testing detected significantly more cancers than did FIT but had more false positive results. (Funded by Exact Sciences; ClinicalTrials.gov number, NCT01397747.).

Prospective evaluation of methylated SEPT9 in plasma for detection of asymptomatic colorectal cancer

BACKGROUND

As screening methods for colorectal cancer (CRC) are limited by uptake and adherence, further options are sought. A blood test might increase both, but none has yet been tested in a screening setting.

OBJECTIVE

We prospectively assessed the accuracy of circulating methylated SEPT9 DNA (mSEPT9) for detecting CRC in a screening population.

DESIGN

Asymptomatic individuals ≥50 years old scheduled for screening colonoscopy at 32 US and German clinics voluntarily gave blood plasma samples before colon preparation. Using a commercially available assay, three independent blinded laboratories assayed plasma DNA of all CRC cases and a stratified random sample of other subjects in duplicate real time PCRs. The primary outcomes measures were standardised for overall sensitivity and specificity estimates.

RESULTS

7941 men (45%) and women (55%), mean age 60 years, enrolled. Results from 53 CRC cases and from 1457 subjects without CRC yielded a standardised sensitivity of 48.2% (95% CI 32.4% to 63.6%; crude rate 50.9%); for CRC stages I-IV, values were 35.0%, 63.0%, 46.0% and 77.4%, respectively. Specificity was 91.5% (95% CI 89.7% to 93.1%; crude rate 91.4%). Sensitivity for advanced adenomas was low (11.2%).

CONCLUSIONS

Our study using the blood based mSEPT9 test showed that CRC signal in blood can be detected in asymptomatic average risk individuals undergoing screening. However, the utility of the test for population screening for CRC will require improved sensitivity for detection of early cancers and advanced adenomas.

CLINICAL TRIAL REGISTRATION NUMBER

NCT00855348.

Cultivating cohort studies for observational translational research

BACKGROUND

"Discovery" research about molecular markers for diagnosis, prognosis, or prediction of response to therapy has frequently produced results that were not reproducible in subsequent studies. What are the reasons, and can observational cohorts be cultivated to provide strong and reliable answers to those questions? Experimental

METHODS

Selected examples are used to illustrate: (i) what features of research design provide strength and reliability in observational studies about markers of diagnosis, prognosis, and response to therapy? (ii) How can those design features be cultivated in existing observational cohorts, for example, within randomized controlled clinical trial (RCT), other existing observational research studies, or practice settings like health maintenance organization (HMOs)?

RESULTS

Examples include a study of RNA expression profiles of tumor tissue to predict prognosis of breast cancer, a study of serum proteomics profiles to diagnose ovarian cancer, and a study of stool-based DNA assays to screen for colon cancer. Strengths and weaknesses of observational study design features are discussed, along with lessons about how features that help assure strength might be "cultivated" in the future.

CONCLUSIONS AND IMPACT

By considering these examples and others, it may be possible to develop a process of "cultivating cohorts" in ongoing RCTs, observational cohort studies, and practice settings like HMOs that have strong features of study design. Such an effort could produce sources of data and specimens to reliably answer questions about the use of molecular markers in diagnosis, prognosis, and response to therapy.

Transforming epidemiology for 21st century medicine and public health

In 2012, the National Cancer Institute (NCI) engaged the scientific community to provide a vision for cancer epidemiology in the 21st century. Eight overarching thematic recommendations, with proposed corresponding actions for consideration by funding agencies, professional societies, and the research community emerged from the collective intellectual discourse. The themes are (i) extending the reach of epidemiology beyond discovery and etiologic research to include multilevel analysis, intervention evaluation, implementation, and outcomes research; (ii) transforming the practice of epidemiology by moving toward more access and sharing of protocols, data, metadata, and specimens to foster collaboration, to ensure reproducibility and replication, and accelerate translation; (iii) expanding cohort studies to collect exposure, clinical, and other information across the life course and examining multiple health-related endpoints; (iv) developing and validating reliable methods and technologies to quantify exposures and outcomes on a massive scale, and to assess concomitantly the role of multiple factors in complex diseases; (v) integrating "big data" science into the practice of epidemiology; (vi) expanding knowledge integration to drive research, policy, and practice; (vii) transforming training of 21st century epidemiologists to address interdisciplinary and translational research; and (viii) optimizing the use of resources and infrastructure for epidemiologic studies. These recommendations can transform cancer epidemiology and the field of epidemiology, in general, by enhancing transparency, interdisciplinary collaboration, and strategic applications of new technologies. They should lay a strong scientific foundation for accelerated translation of scientific discoveries into individual and population health benefits.

Tailoring colorectal cancer screening by considering risk of advanced proximal neoplasia

BACKGROUND

Quantifying the risk of advanced proximal colorectal neoplasia might allow tailoring of colorectal cancer screening, with colonoscopy for those at high risk and less invasive screening for very low-risk persons.

METHODS

We analyzed findings from 10,124 consecutive adults aged≥50 years who underwent screening colonoscopy to the cecum. We quantified the risk of advanced neoplasia (tubular adenoma≥1 cm, a polyp with villous histology or high-grade dysplasia, or adenocarcinoma) both proximally (cecum to splenic flexure) and distally (descending colon to anus). The prevalence of advanced proximal neoplasia was quantified by age, gender, and distal findings.

RESULTS

The mean (standard deviation) age was 57.5 (6.0) years; 44% were women; 7835 (77%) had no neoplasia, and 1856 (18%) had 1 or more nonadvanced adenomas. Overall, 433 subjects (4.3%) had advanced neoplasia (267 distally, 196 proximally, 30 both), 33 (0.33%) of which were adenocarcinoma (18 distal, 15 proximal). The risk of advanced proximal neoplasia increased with age decade (1.13%, 2.00%, and 5.26%, respectively; P=.001) and was higher in men (relative risk [RR], 1.91; confidence interval [CI], 1.32-2.77). In women aged less than 70 years, the risk was 1.1% overall (vs 2.2% in men; RR, 1.98; CI, 1.42-2.76) and 0.86% in those with no distal neoplasia (vs 1.54% in men; RR, 1.81; CI, 1.20-2.74).

CONCLUSIONS

Risk of advanced proximal neoplasia is a function of age and gender. Women aged less than 60 to 70 years have a very low risk, particularly those with no distal adenoma. Sigmoidoscopy with or without occult blood testing may be sufficient and even preferable for screening these subgroups.

Risk for colorectal cancer in persons with a family history of adenomatous polyps: a systematic review

BACKGROUND

The risk for colorectal cancer (CRC) is unclear for persons who have first-degree relatives with adenomatous polyps (adenomas).

PURPOSE

To determine the validity of studies about this issue.

DATA SOURCES

MEDLINE and Cochrane databases from 1966 through 2011.

STUDY SELECTION

Sequential review of titles, abstracts, and text from retrieved articles.

DATA EXTRACTION

Study objective, study design, and numbers in study groups.

DATA SYNTHESIS

Ten studies were identified that have been used to answer the question, "Does having a first-degree relative with an adenoma increase the risk for CRC?" We determined that they instead answer the question, "Does having a first-degree relative with CRC increase the risk for an adenoma?" We identified 2 additional studies that provide more relevant information. One study showed that the risk for CRC in persons who have first-degree relatives with adenomas is greater than the risk in persons who do not have first-degree relatives with adenomas (2.31% vs. 0.53%; relative risk, 4.36 [95% CI, 1.60 to 10.21]). The other study showed that the risk for CRC or large adenomas (≥1 cm) in persons who have first-degree relatives with large adenomas is greater than the risk in persons whose first-degree relatives do not have adenomas or CRC (8.3% vs. 4.2%; adjusted odds ratio, 2.27 [CI, 1.01 to 5.09]).

LIMITATION

Even the 2 relevant studies have design problems that affect validity and generalizability.

CONCLUSION

Most studies that are cited for the risk for CRC when relatives have adenomas do not address the issue. The 2 studies that do address the issue suggest an increased risk but have important methodological limitations. Properly designed studies are needed to measure the risk and identify the factors that modify it.

Bone-density testing interval and transition to osteoporosis in older women

BACKGROUND

Although bone mineral density (BMD) testing to screen for osteoporosis (BMD T score, -2.50 or lower) is recommended for women 65 years of age or older, there are few data to guide decisions about the interval between BMD tests.

METHODS

We studied 4957 women, 67 years of age or older, with normal BMD (T score at the femoral neck and total hip, -1.00 or higher) or osteopenia (T score, -1.01 to -2.49) and with no history of hip or clinical vertebral fracture or of treatment for osteoporosis, followed prospectively for up to 15 years. The BMD testing interval was defined as the estimated time for 10% of women to make the transition to osteoporosis before having a hip or clinical vertebral fracture, with adjustment for estrogen use and clinical risk factors. Transitions from normal BMD and from three subgroups of osteopenia (mild, moderate, and advanced) were analyzed with the use of parametric cumulative incidence models. Incident hip and clinical vertebral fractures and initiation of treatment with bisphosphonates, calcitonin, or raloxifene were treated as competing risks.

RESULTS

The estimated BMD testing interval was 16.8 years (95% confidence interval [CI], 11.5 to 24.6) for women with normal BMD, 17.3 years (95% CI, 13.9 to 21.5) for women with mild osteopenia, 4.7 years (95% CI, 4.2 to 5.2) for women with moderate osteopenia, and 1.1 years (95% CI, 1.0 to 1.3) for women with advanced osteopenia.

CONCLUSIONS

Our data indicate that osteoporosis would develop in less than 10% of older, postmenopausal women during rescreening intervals of approximately 15 years for women with normal bone density or mild osteopenia, 5 years for women with moderate osteopenia, and 1 year for women with advanced osteopenia. (Funded by the National Institutes of Health.).

A framework for evaluating biomarkers for early detection: validation of biomarker panels for ovarian cancer

A panel of biomarkers may improve predictive performance over individual markers. Although many biomarker panels have been described for ovarian cancer, few studies used prediagnostic samples to assess the potential of the panels for early detection. We conducted a multisite systematic evaluation of biomarker panels using prediagnostic serum samples from the Prostate, Lung, Colorectal, and Ovarian Cancer (PLCO) screening trial. Using a nested case-control design, levels of 28 biomarkers were measured laboratory-blinded in 118 serum samples obtained before cancer diagnosis and 951 serum samples from matched controls. Five predictive models, each containing 6 to 8 biomarkers, were evaluated according to a predetermined analysis plan. Three sequential analyses were conducted: blinded validation of previously established models (step 1); simultaneous split-sample discovery and validation of models (step 2); and exploratory discovery of new models (step 3). Sensitivity, specificity, sensitivity at 98% specificity, and AUC were computed for the models and CA125 alone among 67 cases diagnosed within one year of blood draw and 476 matched controls. In step 1, one model showed comparable performance to CA125, with sensitivity, specificity, and AUC at 69.2%, 96.6%, and 0.892, respectively. Remaining models had poorer performance than CA125 alone. In step 2, we observed a similar pattern. In step 3, a model derived from all 28 markers failed to show improvement over CA125. Thus, biomarker panels discovered in diagnostic samples may not validate in prediagnostic samples; utilizing prediagnostic samples for discovery may be helpful in developing validated early detection panels.

Principles of cancer screening: lessons from history and study design issues

Early detection of cancer has held great promise and intuitive appeal in the medical community for well over a century. Its history developed in tandem with that of the periodic health examination, in which any deviations--subtle or glaring--from a clearly demarcated "normal" were to be rooted out, given the underlying hypothesis that diseases develop along progressive linear paths of increasing abnormalities. This model of disease development drove the logical deduction that early detection, by "breaking the chain" of cancer development, must be of benefit to affected individuals. In the latter half of the 20th century, researchers and guidelines organizations began to explicitly challenge the core assumptions underpinning many clinical practices. A move away from intuitive thinking began with the development of evidence-based medicine. One key method developed to explicitly quantify the overall risk-benefit profile of a given procedure was the analytic framework. The shift away from pure deductive reasoning and reliance on personal observation was driven, in part, by a rising awareness of critical biases in cancer screening that can mislead clinicians, including healthy volunteer bias, length-biased sampling, lead-time bias, and overdiagnosis. A new focus on the net balance of both benefits and harms when determining the overall worth of an intervention also arose: it was recognized that the potential downsides of early detection were frequently overlooked or discounted because screening is performed on basically healthy persons and initially involves relatively noninvasive methods. Although still inconsistently applied to early detection programs, policies, and belief systems in the United States, an evidence-based approach is essential to counteract the misleading--even potentially harmful--allure of intuition and individual observation.

Understanding differences in the guidelines for colorectal cancer screening

In this issue of Gastroenterology, the editors present 2 expert perspectives on the colorectal screening guidelines published in the May 2008 issue of the journal.

Sources of bias in specimens for research about molecular markers for cancer

Claims about the diagnostic or prognostic accuracy of markers often prove disappointing when "discrimination" found between cancers versus normals is due to bias, a systematic difference between compared groups. This article describes a framework to help simplify and organize current problems in marker research by focusing on the role of specimens as a source of bias in observational research and using that focus to address problems and improve reliability. The central idea is that the "fundamental comparison" in research about markers (ie, the comparison done to assess whether a marker discriminates) involves two distinct processes that are "connected" by specimens. If subject selection (first process) creates baseline inequality between groups being compared, then laboratory analysis of specimens (second process) may erroneously find positive results. Although both processes are important, subject selection more fundamentally influences the quality of marker research, because it can hardwire bias into all comparisons in a way that cannot be corrected by any refinement in laboratory analysis. An appreciation of the separateness of these two processes-and placing investigators with appropriate expertise in charge of each-may increase the reliability of research about cancer biomarkers.

Proteomics research to discover markers: what can we learn from Netflix?

BACKGROUND

Research in the field of proteomics to discover markers for detection of cancer has produced disappointing results, with few markers gaining US Food and Drug Administration approval, and few claims borne out when subsequently tested in rigorous studies. What is the role of better mathematical or statistical analysis in improving the situation?

CONTENT

This article examines whether a recent successful Netflix-sponsored competition using mathematical analysis to develop a prediction model for movie ratings of individual subscribers can serve to improve studies of markers in the field of proteomics. Netflix developed a database of movie preferences of individual subscribers using a longitudinal cohort research design. Groups of researchers then competed to develop better ways to analyze the data. Against this background, the strengths and weaknesses of research design are reviewed, contrasting the Netflix design with that of studies of biomarkers to detect cancer. Such biomarker studies generally have less-strong design, lower numbers of outcomes, and greater difficulty in even just measuring predictors and outcomes, so the fundamental data that will be used in mathematical analysis tend to be much weaker than in other kinds of research.

CONCLUSIONS

If the fundamental data that will be analyzed are not strong, then better analytic methods have limited use in improving the situation. Recognition of this situation is an important first step toward improving the quality of clinical research about markers to detect cancer.

Protein-based multiplex assays: mock presubmissions to the US Food and Drug Administration

As a part of ongoing efforts of the NCI-FDA Interagency Oncology Task Force subcommittee on molecular diagnostics, members of the Clinical Proteomic Technology Assessment for Cancer program of the National Cancer Institute have submitted 2 protein-based multiplex assay descriptions to the Office of In Vitro Diagnostic Device Evaluation and Safety, US Food and Drug Administration. The objective was to evaluate the analytical measurement criteria and studies needed to validate protein-based multiplex assays. Each submission described a different protein-based platform: a multiplex immunoaffinity mass spectrometry platform for protein quantification, and an immunological array platform quantifying glycoprotein isoforms. Submissions provided a mutually beneficial way for members of the proteomics and regulatory communities to identify the analytical issues that the field should address when developing protein-based multiplex clinical assays.

Analytical validation of protein-based multiplex assays: a workshop report by the NCI-FDA interagency oncology task force on molecular diagnostics

Clinical proteomics has the potential to enable the early detection of cancer through the development of multiplex assays that can inform clinical decisions. However, there has been some uncertainty among translational researchers and developers as to the specific analytical measurement criteria needed to validate protein-based multiplex assays. To begin to address the causes of this uncertainty, a day-long workshop titled "Interagency Oncology Task Force Molecular Diagnostics Workshop" was held in which members of the proteomics and regulatory communities discussed many of the analytical evaluation issues that the field should address in development of protein-based multiplex assays for clinical use. This meeting report explores the issues raised at the workshop and details the recommendations that came out of the day's discussions, such as a workshop summary discussing the analytical evaluation issues that specific proteomic technologies should address when seeking US Food and Drug Administration approval.

The Scientific Foundation for personal genomics: recommendations from a National Institutes of Health-Centers for Disease Control and Prevention multidisciplinary workshop

The increasing availability of personal genomic tests has led to discussions about the validity and utility of such tests and the balance of benefits and harms. A multidisciplinary workshop was convened by the National Institutes of Health and the Centers for Disease Control and Prevention to review the scientific foundation for using personal genomics in risk assessment and disease prevention and to develop recommendations for targeted research. The clinical validity and utility of personal genomics is a moving target with rapidly developing discoveries but little translation research to close the gap between discoveries and health impact. Workshop participants made recommendations in five domains: (1) developing and applying scientific standards for assessing personal genomic tests; (2) developing and applying a multidisciplinary research agenda, including observational studies and clinical trials to fill knowledge gaps in clinical validity and utility; (3) enhancing credible knowledge synthesis and information dissemination to clinicians and consumers; (4) linking scientific findings to evidence-based recommendations for use of personal genomics; and (5) assessing how the concept of personal utility can affect health benefits, costs, and risks by developing appropriate metrics for evaluation. To fulfill the promise of personal genomics, a rigorous multidisciplinary research agenda is needed.

Adverse events after outpatient colonoscopy in the Medicare population

BACKGROUND

Although use of colonoscopy has increased substantially among elderly Medicare beneficiaries, no one has described colonoscopy-related adverse events in a representative sample of Medicare patients.

OBJECTIVE

To determine risk for adverse events after outpatient colonoscopy in elderly patients.

DESIGN

Population-based, matched cohort study.

SETTING

Surveillance, Epidemiology, and End Results cancer registry areas.

PATIENTS

Random 5% sample of Medicare beneficiaries, age 66 to 95 years, who underwent outpatient colonoscopy between 1 July 2001 and 31 October 2005 (n = 53 220), matched with beneficiaries who did not have colonoscopy.

MEASUREMENTS

Medicare claims were used to measure the rate of serious gastrointestinal events (bleeding and perforation), other gastrointestinal events, and cardiovascular events resulting in a hospitalization or emergency department visit within 30 days after colonoscopy compared with matched beneficiaries who did not have colonoscopy. Logistic regression was used to estimate adjusted predictive risks for adverse events and to assess whether these events varied by age, comorbid conditions, or type of colonoscopy.

RESULTS

Persons undergoing colonoscopy had a higher risk for adverse gastrointestinal events than their matched group. Rates of adverse events after colonoscopy increased with age. Patients having polypectomy had higher risk for all adverse events compared with their matched group and with the screening and diagnostic colonoscopy groups. Comorbid conditions increased the risk for adverse events. Patients with a history of stroke, chronic obstructive pulmonary disease, atrial fibrillation, or congestive heart failure had significantly higher risk for serious gastrointestinal events.

LIMITATION

The analysis relied on the diagnosis and procedure codes recorded on the Medicare claims.

CONCLUSION

Risks for adverse events after outpatient colonoscopy among elderly Medicare beneficiaries were low; however, they increased with age with specific comorbid conditions and depending on whether polypectomy was done. These data may inform decisions on whether to perform colonoscopy in persons of advanced age or those with comorbid conditions.

Promises and limitations of biomarkers

In many "omics" fields, extraordinary promises have been made about the ability of biomarkers for detecting early cancer, for predicting prognosis, and for predicting response to therapy. Yet very few markers are brought to clinical practice, and many are not even found to be reproducible. This essay discusses chance and bias as threats to validity that can explain the huge disconnect between promise and product, along with approaches to address those threats.

Assessment of serum proteomics to detect large colon adenomas

A noninvasive blood test that could reliably detect early colorectal cancer or large adenomas would provide an important advance in colon cancer screening. The purpose of this study was to determine whether a serum proteomics assay could discriminate between persons with and without a large (> or =1 cm) colon adenoma. To avoid problems of "bias" that have affected many studies about molecular markers for diagnosis, specimens were obtained from a previously conducted study of colorectal cancer etiology in which bloods had been collected before the presence or absence of neoplasm had been determined by colonoscopy, helping to assure that biases related to differences in sample collection and handling would be avoided. Mass spectra of 65 unblinded serum samples were acquired using a nanoelectrospray ionization source on a QSTAR-XL mass spectrometer. Classification patterns were developed using the ProteomeQuest algorithm, performing measurements twice on each specimen, and then applied to a blinded validation set of 70 specimens. After removing 33 specimens that had discordant results, the "test group" comprised 37 specimens that had never been used in training. Although in the primary analysis, no discrimination was found, a single post hoc analysis, done after hemolyzed specimens had been removed, showed a sensitivity of 78%, a specificity of 53%, and an accuracy of 63% (95% confidence interval, 53-72%). The results of this study, although preliminary, suggest that further study of serum proteomics, in a larger number of appropriate specimens, could be useful. They also highlight the importance of understanding sources of "noise" and "bias" in studies of proteomics assays.