Five-year risk of colorectal neoplasia after negative screening colonoscopy

BACKGROUND

The appropriate interval for endoscopic rescreening after a negative colonoscopic examination is uncertain.

METHODS

We identified persons with no adenomas on baseline screening colonoscopy who returned at 5 years for follow-up colonoscopy. Findings were categorized according to the most advanced lesion present: no polyp, a hyperplastic polyp, a tubular adenoma less than 1 cm in diameter, an advanced adenoma (a tubular adenoma > or = 1 cm in diameter or a polyp with villous histologic features or high-grade dysplasia), or a cancer.

RESULTS

Baseline screening colonoscopy had identified 2436 persons with no adenomas; 1256 of them (51.6%) were rescreened a mean (+/-SD) of 5.34+/-1.34 years later. The mean age of this group at baseline was 56.7 years; 56.7% of its members were men. No cancers were found on rescreening (95% confidence interval [CI] for the detection rate, 0 to 0.24%). One or more adenomas were found in 201 persons (16.0%). A total of 19 advanced adenomas, of which 10 (52.6%) were distal to the splenic flexure, were found in 16 persons (1.3%). The risk of an advanced adenoma did not differ significantly between persons with no polyps at baseline and those with hyperplastic polyps at baseline (1.1% [12 of 1057] and 2.0% [4 of 199], respectively; P=0.30). Men were more likely than women to have any adenoma (tubular less than 1 cm in diameter or advanced) (relative risk, 1.88; 95% CI, 1.42 to 2.51) and to have an advanced adenoma (relative risk, 3.31; 95% CI, 1.02 to 10.8).

CONCLUSIONS

Among persons with no colorectal neoplasia on initial screening colonoscopy, the 5-year risk of colorectal cancer is extremely low. The risk of advanced adenoma is also low, although it is higher among men than among women. Our findings support a rescreening interval of 5 years or longer after a normal colonoscopic examination.

Evaluation of claims, medical records, and self-report for measuring fecal occult blood testing among medicare enrollees in fee for service

BACKGROUND

There is no agreement on the best data source for measuring colorectal cancer (CRC) screening. Medicare claims have been used to measure CRC testing but the validity of using claims to measure fecal occult blood tests (FOBT) has not been established.

METHODS

We compared ascertainment of FOBT among three data sources: self-reports, Medicare claims, and medical records. Data were collected on FOBT use during the study window (1/1/1998 - 12/31/2002). Our study was conducted with North Carolina Medicare enrollees (N = 561) who had previously responded to a telephone survey on CRC tests. FOBT information was abstracted from respondents' physician office medical records and compared with self-reported FOBT use and Medicare claims for FOBT. Data sources were assessed for accuracy and completeness of FOBT reporting using sensitivity, specificity, positive predictive value, negative predictive value, and agreement.

RESULTS

Reporting of FOBT use in the prior year in medical records and Medicare claims agreed 82% of the time [95% confidence interval (95% CI), 79-85%]. FOBT 1-year use rates from self-report agreed with test use found in medical records 70% of the time (95% CI, 66-74%). The lowest agreement was between self-reported 1-year FOBT use and Medicare claims, which agreed 67% of the time (95% CI, 63-71%).

CONCLUSIONS

No data source could be established as providing complete and valid information about FOBT use among Medicare enrollees, showing the difficulty of ascertaining test use rates for noninvasive, low-cost procedures conducted in multiple settings. Caution should be used when attempting to measure FOBT use with self-report, Medicare claims, or medical records.

Data sources for measuring colorectal endoscopy use among Medicare enrollees

BACKGROUND

Estimates of colorectal cancer test use vary widely by data source. Medicare claims offer one source for monitoring test use, but their utility has not been validated. We compared ascertainment of sigmoidoscopy and colonoscopy between three data sources: self reports, Medicare claims, and medical records.

MATERIALS AND METHODS

The study population included Medicare enrollees residing in North Carolina (n = 561) who had participated in a telephone survey on colorectal cancer tests. Medicare claims were obtained for the 5 years preceding the survey (January 1, 1998 to December 31, 2002). Information about sigmoidoscopy and colonoscopy procedures conducted in physician offices were abstracted from medical records. Sensitivity, specificity, positive predictive value, negative predictive value, agreement, and kappa statistics were calculated using the medical record as the gold standard. Agreement on specific procedure type and purpose was also assessed.

RESULTS

Agreement between claim and medical record regarding whether an endoscopic procedure had been done was high (over 90%). Agreement between self report and medical record and between self report and claim was good (79% and 74%, respectively). All three data sources adequately distinguished the type of procedure done. None of the data sources showed reliable levels of agreement regarding procedure purpose (screening or diagnostic).

CONCLUSION

Medicare claims can provide accurate information on whether a patient has undergone colorectal endoscopy and may be more complete than physician medical records. Medicare claims cannot be used to distinguish screening from diagnostic tests. Recognizing this limitation, researchers who use Medicare claims to assess rates of colorectal testing should include both screening and diagnostic endoscopy procedures in their analyses.

Overstating the evidence for lung cancer screening: the International Early Lung Cancer Action Program (I-ELCAP) study

Last year, the New England Journal of Medicine ran a lead article reporting that patients with lung cancer had a 10-year survival approaching 90% if detected by screening spiral computed tomography. The publication garnered considerable media attention, and some felt that its findings provided a persuasive case for the immediate initiation of lung cancer screening. We strongly disagree. In this article, we highlight 4 reasons why the publication does not make a persuasive case for screening: the study had no control group, it lacked an unbiased outcome measure, it did not consider what is already known about this topic from previous studies, and it did not address the harms of screening. We conclude with 2 fundamental principles that physicians should remember when thinking about screening: (1) survival is always prolonged by early detection, even when deaths are not delayed nor any lives saved, and (2) randomized trials are the only way to reliably determine whether screening does more good than harm.

What is the role of iFOBT in screening for colorectal cancer?

Policy makers will need to consider if it has one, not only as an adjunct to gFOBT screening, but also as a primary screening test

Screening for Colorectal Neoplasms With New Fecal Occult Blood Tests: Update on Performance Characteristics

BACKGROUND

One type of fecal occult blood test (FOBT), the unrehydrated guaiac fecal occult blood test (GT), is recommended by the United States Preventive Services Task Force and the Institute of Medicine for use in screening programs, but it has relatively low sensitivity as a single test for detecting advanced colonic neoplasms (cancer and adenomatous polyps > or = 1 cm in diameter). Thus, improving the sensitivity of FOBT should make colon cancer screening programs that use these tests more effective.

METHODS

We assessed prospectively the performance characteristics of two newer FOBTs in 5841 subjects at average risk for colorectal cancer in a large group-model managed care organization. The tests evaluated included a sensitive GT, a fecal immunochemical test (FIT), and the combination of both tests. Patients with positive and negative test results were advised to have colonoscopy and sigmoidoscopy, respectively. Sensitivity and specificity for detecting advanced neoplasms in the left colon within 2 years after the FOBT screening were evaluated for the two tests administered separately and in combination.

RESULTS

A total of 139 patients were diagnosed with advanced colorectal neoplasms (n = 14 cancers, n = 128 adenomas) within the 2 years following their initial FOBT screening. Sensitivity for detecting cancer was 81.8% (95% confidence interval [CI] = 47.8% to 96.8%) for the FIT alone and 64.3% (95% CI = 35.6% to 86.0%) for the sensitive GT and the combination test. Sensitivity for detecting advanced colorectal adenomas was 41.3% (95% CI = 32.7% to 50.4%) for the sensitive GT, 29.5% (95% CI = 21.4% to 38.9%) for the FIT, and 22.8% (95% CI =16.1% to 31.3%) for the combination test. Specificity for detecting cancer and adenomas was 98.1% (95% CI = 97.7% to 98.4%) and 98.4% (95% CI = 98.0% to 98.7%), respectively, for the combination test; 96.9% (95% CI = 96.4% to 97.4%) and 97.3% (95% CI = 96.8% to 97.7%), respectively, for the FIT; and 90.1% (95% CI = 89.3% to 90.8%) and 90.6% (95% CI = 89.8% to 91.4%), respectively, for the sensitive GT.

CONCLUSIONS

The FIT has high sensitivity and specificity for detecting left-sided colorectal cancer, and it may be a useful replacement for the GT.

How to improve reliability and efficiency of research about molecular markers: roles of phases, guidelines, and study design

BACKGROUND AND OBJECTIVE

The search for molecular markers for cancer, using "discovery-based" techniques, has resulted in claims of a very high degree of discrimination both for cancer diagnosis (e.g., serum proteomics patterns) and prognosis (e.g., RNA expression genomic signatures). However, many promising initial results have been found to be unreliable or not reproducible, and the larger process of discovery can seem slow and inefficient. To improve the process to develop molecular markers, proposals to use "phases" and "guidelines" have been made, based on experience with the process of drug development and randomized controlled clinical trials. The objective is to help improve the reliability and efficiency of development of molecular markers for cancer diagnosis.

STUDY DESIGN AND SETTING

The literature was searched to identify important current problems (in serum proteomics for cancer diagnosis and RNA expression genomics for cancer prognosis) are identified, and the roles of tools ("phases," "guidelines," and "study design") to address those problems are considered. Based on lessons learned, approaches for the future are discussed, some of which may seem "radical" compared with drug development.

RESULTS

Phases identify and organize questions to be addressed by individual studies. Guidelines identify features of design and conduct to be reported so that each study's reliability can be judged. Study design involves the myriad details and choices involved in actual planning and conduct of a study. Study design is most important in the sense of determining whether a study is reliable or not. Studies that are unreliable, because of problems from chance and bias, constitute a major current problem leading to inflated expectations, wasted effort, and inefficiency in the larger process of development. By considering fundamental principles, it may be possible to identify approaches that are different than those used in drug development, while preserving reliability and efficiency.

CONCLUSION

Phases and guidelines have important roles, but issues in study design address the fundamental problems that compromise reliability and efficiency. Tools to study markers are underdeveloped and will evolve over time, perhaps to include seemingly radical approaches.

Improving colorectal cancer screening in primary care practice: innovative strategies and future directions

Colorectal cancer (CRC) screening has been supported by strong research evidence and recommended in clinical practice guidelines for more than a decade. Yet screening rates in the United States remain low, especially relative to other preventable diseases such as breast and cervical cancer. To understand the reasons, the National Cancer Institute and Agency for Healthcare Research and Quality sponsored a review of CRC screening implementation in primary care and a program of research funded by these organizations. The evidence base for improving CRC screening supports the value of a New Model of Primary Care Delivery: 1. a team approach, in which responsibility for screening tasks is shared among other members of the practice, would help address physicians' lack of time for preventive care; 2. information systems can identify eligible patients and remind them when screening is due; 3. involving patients in decisions about their own care may enhance screening participation; 4. monitoring practice performance, supported by information systems, can help target patients at increased risk because of family history or social disadvantage; 5. reimbursement for services outside the traditional provider-patient encounter, such as telephone and e-mail contacts, may foster enhanced screening delivery; 6. training opportunities in communication, cultural competence, and use of information technologies would improve provider competence in core elements of screening programs. Improvement in CRC screening rates largely depends on the efforts of primary care practices to implement effective systems and procedures for screening delivery. Active engagement and support of practices are essential for the enormous potential of CRC screening to be realized.

Lessons from controversy: ovarian cancer screening and serum proteomics

In 2002 a study reported that a blood test, based on pattern-recognition proteomics mass spectroscopy analysis of serum, was nearly 100% sensitive and specific to detect ovarian cancer. Plans to introduce a commercial screening test by early 2004 were delayed amid concerns about whether the approach was reproducible and reliable. In this issue of JNCI, two commentaries discuss whether the initial results are reproducible and whether bias may account for results. This essay describes how threats to validity from chance and bias may cause erroneous results and inflated expectations in the kind of observational research being conducted in several "-omics" fields to assess molecular markers for diagnosis and prognosis of cancer. To address such threats and to realize the potential of new -omics technology will require application of appropriate rules of evidence in the design, conduct, and interpretation of clinical research about molecular markers.

Bias as a threat to the validity of cancer molecular-marker research

Claims that molecular markers can accurately diagnose cancer have recently been disputed; some prominent results have not been reproduced and bias has been proposed to explain the original observations. As new '-omics' fields are explored to assess molecular markers for cancer, bias will increasingly be recognized as the most important 'threat to validity' that must be addressed in the design, conduct and interpretation of such research.

A national survey of primary care physicians' methods for screening for fecal occult blood

BACKGROUND

Screening with the fecal occult blood test (FOBT) has been shown to reduce colorectal cancer incidence and mortality in randomized, controlled trials. Although the test is simple, implementation requires adherence to specific techniques of testing and follow-up of abnormal results.

OBJECTIVE

To examine how FOBT and follow-up are conducted in community practice across the United States.

DESIGN

Cross-sectional national surveys of primary care physicians and the public.

SETTING

The Survey of Colorectal Cancer Screening Practices in Health Care Organizations and the 2000 National Health Interview Survey.

PARTICIPANTS

1147 primary care physicians who ordered or performed FOBT and 11 365 adults 50 years of age or older who responded to questions about FOBT use.

MEASUREMENTS

Self-reported data on details of FOBT implementation and follow-up of positive results.

RESULTS

Although screening guidelines recommend home tests, 32.5% (95% CI, 29.8% to 35.3%) of physicians used only the less accurate method of single-sample in-office testing; another 41.2% (CI, 38.3% to 44.0%) used both types of test. Follow-up of positive test results showed considerable nonadherence to guidelines, with 29.7% (CI, 27.1% to 32.4%) of physicians recommending repeating FOBT. Furthermore, sigmoidoscopy, rather than total colon examination, was commonly recommended to work up abnormal findings. Nearly one third of adults who reported having FOBT said they had only an in-office test, and nearly one third of those who reported abnormal FOBT results reported no follow-up diagnostic procedures.

LIMITATIONS

The study was based on self-reports. Data from the National Health Interview Survey may underestimate the prevalence of in-office testing and inadequate follow-up.

CONCLUSIONS

Mortality reductions demonstrated with FOBT in clinical trials may not be realized in community practice because of the common use of in-office tests and inappropriate follow-up of positive results. Education of providers and system-level interventions are needed to improve the quality of screening implementation.

Fecal DNA versus fecal occult blood for colorectal-cancer screening in an average-risk population

BACKGROUND

Although fecal occult-blood testing is the only available noninvasive screening method that reduces the risk of death from colorectal cancer, it has limited sensitivity. We compared an approach that identifies abnormal DNA in stool samples with the Hemoccult II fecal occult-blood test in average-risk, asymptomatic persons 50 years of age or older.

METHODS

Eligible subjects submitted one stool specimen for DNA analysis, underwent standard Hemoccult II testing, and then underwent colonoscopy. Of 5486 subjects enrolled, 4404 completed all aspects of the study. A subgroup of 2507 subjects was analyzed, including all those with a diagnosis of invasive adenocarcinoma or advanced adenoma plus randomly chosen subjects with no polyps or minor polyps. The fecal DNA panel consisted of 21 mutations.

RESULTS

The fecal DNA panel detected 16 of 31 invasive cancers, whereas Hemoccult II identified 4 of 31 (51.6 percent vs. 12.9 percent, P=0.003). The DNA panel detected 29 of 71 invasive cancers plus adenomas with high-grade dysplasia, whereas Hemoccult II identified 10 of 71 (40.8 percent vs. 14.1 percent, P<0.001). Among 418 subjects with advanced neoplasia (defined as a tubular adenoma at least 1 cm in diameter, a polyp with a villous histologic appearance, a polyp with high-grade dysplasia, or cancer), the DNA panel was positive in 76 (18.2 percent), whereas Hemoccult II was positive in 45 (10.8 percent). Specificity in subjects with negative findings on colonoscopy was 94.4 percent for the fecal DNA panel and 95.2 percent for Hemoccult II.

CONCLUSIONS

Although the majority of neoplastic lesions identified by colonoscopy were not detected by either noninvasive test, the multitarget analysis of fecal DNA detected a greater proportion of important colorectal neoplasia than did Hemoccult II without compromising specificity.

Are physicians doing too much colonoscopy? A national survey of colorectal surveillance after polypectomy

BACKGROUND

Increasing use of colonoscopy for colorectal cancer screening and surveillance of colorectal adenomas after polypectomy has given rise to concerns about the availability of endoscopic resources in the United States. Guidelines recommend surveillance after polypectomy at 3 to 5 years for a small adenoma, and follow-up is not advised for hyperplastic polyps. The intensity of physicians' surveillance is largely unstudied.

OBJECTIVE

To survey practicing gastroenterologists and general surgeons about their perceived need for the frequency of surveillance after polypectomy, to compare survey responses to practice guidelines, and to identify factors influencing their recommendations for surveillance.

DESIGN

Survey study conducted by the National Cancer Institute.

SETTING

A nationally representative study of physicians in the United States.

PARTICIPANTS

349 gastroenterologists and 316 general surgeons.

MEASUREMENTS

Questionnaires mailed in 1999 and 2000 assessed physicians' recommendations for surveillance after polypectomy in asymptomatic, average-risk patients.

RESULTS

Response rates were 83%. Among gastroenterologists (317 of 349) and surgeons (125 of 316) who perform screening colonoscopy, 24% (95% CI, 19.3% to 28.7%) of gastroenterologists and 54% (CI, 44.9% to 62.5%) of surgeons recommend surveillance for a hyperplastic polyp. For a small adenoma, most physicians recommended surveillance colonoscopy and more than 50% recommended examinations every 3 years or more often. Physicians indicated that published evidence was very influential in their practice (83% [CI, 78.8% to 87.2%] of gastroenterologists and 78% [CI, 72.5% to 86.8%] of surgeons). By contrast, only half of respondents reported that guidelines were very influential.

LIMITATIONS

The study was based on physicians' self-reported practice patterns. Results may overestimate or underestimate the performance of surveillance colonoscopy.

CONCLUSIONS

Some surveillance colonoscopy seems to be inappropriately performed and in excess of guidelines, particularly for hyperplastic polyps and low-risk lesions such as a small adenoma. These results suggest unnecessary demand for endoscopic resources.