The earlier detection of colorectal cancers: a preliminary report of the results of the Occult Blood Study

Selection Criteria in Colorectal Cancer Screening

The authors report the results of a risk questionnaire (RQ) used in a population-based screening program for colorectal cancer. The positive predictive value (PPV) for cancer or adenoma was evaluated for the Hemoccult test (HO) and for all RQ items (symptoms, personal and familial risk) in 8,114 cases, by univariate and multivariate analysis. A significant correlation with the presence of cancer or adenoma was observed for HO-positive tests, whereas a significant correlation was absent for most RQ variables. The use of an RQ in screening practice is disregarded since it does not improve the rate of cancer detection. Moreover, the increase in the detection rate of HO-negative adenomas does not justify the high rate (0.18) of screening responders selected for endoscopic diagnostic workup, a figure which influences negatively the overall compliance to screening.

Early detection of colon cancer-the kaiser permanente northwest 30-year history: how do we measure success? Is it the test, the number of tests, the stage, or the percentage of screen-detected patients?

INTRODUCTION

Colorectal cancer (CRC) is the fourth most common malignancy in the Kaiser Permanente Northwest (KPNW) Region. The goals of CRC screening are early diagnosis of cancer in the preclinical state, down-staging of tumors, and increasing survival. This historical review summarizes the screening strategies since 1980 and their impact on early diagnosis, stage, and survival. During this period, the KPNW Tumor Registry documented the stage and survival, and screen-detection status of patients. We have observed that the percentage of screen-detected case measure has provided critical information that has contributed to the present success. CRC screening efforts by the end of 2010 had provided early diagnosis for one-third of patients.

METHODS

KPNW membership has undergone more than 540,000 fecal blood tests, an estimated 130,000 flexible sigmoidoscopies (FS), and more than 100,000 colonoscopies. Since 1980 members older than age 50 years have increased from 48,627 to 137,617. This report represents a review of 5458 patients. Since 1980, 5 distinct periods of CRC screening have been compared. In 1980, the CRC screening practice was primarily office-based fecal occult blood testing (FOBT) and proctosigmoidoscopy. Data from the initial home-based FOBT testing initiative (1985), transitioning to an FS program (1995), adoption of colonoscopy (2005), and subsequent reintroduction of FOBT testing (2006) allows examination of results by period. After ever-increasing promotion of endoscopy, the goal of screening shifted from "screen detection to prevention by polypectomy."

RESULTS

By reexamining the outcomes of the CRC strategies from 1980-2005, the nature of the colonoscopy label of "gold standard" was questioned leading to a return to FOBT testing. Since then, the percentage of screen-detected patients exceeded expectations with a 6-fold increase (5% to 33%) allowing KPNW to reach its highest level of early detection.

DISCUSSION

By examining the KPNW experience, we have come to better understand the significance of effectiveness measures: number of tests, stage of disease, percentage of screen-detected cancers and their relationship to survival. We examined the measures used to assess success and conclude that the current metrics-the number of examinations and disease stage-do not accurately reflect the effectiveness of screening efforts. Early detection of CRC saves lives when a program tests the most at-risk people. Using a good test (FOBT/fecal immunochemical test) that is able to reach more people, rather than the "perfect test" that reaches fewer people, transforms an ineffective program into a successful one. A critical element was the transition of the individual testing to population screening.

An Overview of Colorectal Cancer Screening

Colorectal cancer ranks highly amongst all cancer sites in incidence and contributes to a substantial number of cancer related deaths in the United Kingdom. However, screening of average risk individuals has been shown to reduce both disease associated mortality and incidence. This paper provides an overview of both current and future screening methods for colorectal cancer, as well as current practice for screening in both average and high risk individuals.

Effective screening for bowel cancer: a United kingdom perspective

Bowel cancer is a major cause of morbidity and death and is a high cost to health care systems. Screening currently offers the best chance of improving outcomes from bowel cancer. When introducing screening, the problems encountered in other cancers need to be avoided to maximize benefits and minimize harms.

Prospective comparison of air-contrast barium enema and colonoscopy in patients with fecal occult blood: a pilot study

BACKGROUND

The utility of air-contrast barium enema and colonoscopy for evaluation of the colon has been debated. Air-contrast barium enema is less expensive and invasive than colonoscopy, but it also is less sensitive and specific. Further, although air-contrast barium enema may be less painful than colonoscopy, it often is poorly tolerated by patients. Thus, this study compared the sensitivity and the specificity of air-contrast barium enema and colonoscopy for detection of colonic lesions in patients with fecal occult blood.

METHODS

Over a 30-month period, patients with fecal occult blood were recruited. Patients underwent standard air-contrast barium enema, followed by colonoscopy 7 to 14 days later. Colonoscopists were blinded to the results of air-contrast barium enema until the colonoscopy was completed, after which the results were disclosed. If the findings were discrepant, colonoscopy was repeated.

RESULTS

A total of 100 patients were evaluated. Nine air-contrast barium enemas were reported to be inadequate, and the cecum was not intubated at colonoscopy in two patients. In the remaining patients, 5 cancers were identified (1 each cecum, transverse colon, descending colon, sigmoid colon, and rectum) by both studies. Sixty-six polypoid lesions were identified in 30 patients. Diverticula were identified in 42 patients by air-contrast barium enema and in 18 patients by colonoscopy. Air-contrast barium enema detected 3 of 36 polypoid lesions 5 mm or less in diameter, 5 of 15 adenomas 6 to 9 mm in size, and 4 of 15 adenomas 10 mm or greater in diameter (sensitivity 8%, 33%, and 27%, respectively). After excluding patients with diverticula, air-contrast barium enema detected 3 of 7 adenomas 10 mm or greater in size. Overall, 12 polypoid lesions or filling defects were identified by air-contrast barium enema that could not be verified by colonoscopy. The specificity of air-contrast barium enema for lesions 1.0 cm or greater in size was 100%; for those 6 mm or greater, it was 97%.

CONCLUSIONS

Air-contrast barium enema accurately detects colon cancer and diverticula. Its sensitivity for detection of polypoid lesions or adenomas is poor and was confounded by the presence of diverticula.

Fifty landmark discoveries in gastroenterology during the past 50 years. A brief history of modern gastroenterology at the millennium: Part II. Gastrointestinal motility, nutrition, and diseases of the lower gastrointestinal tract, liver, and pancreas

During the last half century, many outstanding discoveries have revolutionized the clinical practice and science of gastroenterology. Although the scientific results are widely disseminated, the discoverers have received inadequate recognition and the history of their discoveries is largely unstudied and unknown. At the millennium, a committee selected 50 landmark discoveries in gastroenterology during the past 50 years. A brief history of each landmark discovery is presented. Part I was presented in the previous issue of Gastroenterology Clinics of North America. Part II presents landmark discoveries in gastrointerintal (GI) motility, clinical trials, nutrition, and diseases of the lower GI tract, liver, biliary tree, and pancreas.

CT and MR colography (virtual colonoscopy): status report

Computed tomography (CT) and magnetic resonance (MR) colography (virtual colonoscopy) are new techniques being developed for the purpose of imaging colorectal polyps and cancer. Limited data are available regarding the performance characteristics of either technique, particularly MR. Initial reports suggest that the sensitivity of CT and MR colography for patients with adenomas > or = 1 cm ranges from 75-90%, and decreases precipitously for smaller polyps. Very early data suggest that the specificity for patient with large adenomas is around 90%, but for patients with adenomas in the 5-9 mm range has been as low as 65%. This review discusses currently available published and abstracted data on CT and MR colography and discusses the real and potential advantages and disadvantages of CT and MR colography compared to current colonic imaging methods. The review discusses problems that must be overcome in order for CT or MR colography to be demonstrated as practical tests, and suggests guidelines for the performance of clinical trials testing the performance characteristics of these methods.

Initial management and follow-up surveillance of patients with colorectal adenomas

The clinical management of patients with adenomas is interesting because of the adenomas' malignant potential, the availability of effective intervention by colonoscopy, and the increasing number of patients having adenomas detected and removed. The current literature on follow-up surveillance is reviewed, and surveillance intervals are suggested based on data from the National Polyp Study. Patients newly diagnosed with three or more adenomas, an adenoma of more than 0.5 cm, or with a family history of colorectal cancer should have surveillance colonoscopy at 3 years following the polypectomy. Surveillance of patients with single, small tubular adenomas can be extended to 5 or more years. Patients with large sessile or malignant adenomas need to have follow-up earlier. Identification and removal of adenomatous polyps have been shown to reduce colorectal cancer incidence.

Randomised controlled trial of faecal-occult-blood screening for colorectal cancer

BACKGROUND

There is growing evidence that faecal-occult-blood (FOB) screening may reduce colorectal cancer (CRC) mortality, but this reduction in CRC mortality has not been shown in an unselected population-based randomised controlled trial. The aim of this study was to assess the effect of FOB screening on CRC mortality in such a setting.

METHODS

Between February, 1981, and January, 1991, 152,850 people aged 45-74 years who lived in the Nottingham area of the UK were recruited to our study. Participants were randomly allocated FOB screening (76,466) or no screening (controls; 76,384). Controls were not told about the study and received no intervention. Screening-group participants were sent a Haemoccult FOB test kit with instructions from their family doctor. FOB tests were not rehydrated and dietary restrictions were imposed only for retesting borderline results. Individuals with negative FOB tests at the first screening, together with those who tested positive but in whom no neoplasia was found on colonoscopy, were invited to take part in further screening every 2 years. Screening was stopped in February, 1995, by which time screening-group participants had been offered FOB tests between three and six times. Screening-group participants who had a positive test were offered full colonoscopy. All participants were followed up until June, 1995. The primary outcome measure was CRC mortality.

FINDINGS

Of the 152,850 individuals recruited to the study, 2599 could not be traced or had emigrated and were excluded from the analysis. Thus, there were 75,253 participants in the screening group and 74,998 controls. 44,838 (59.6%) screening-group participants completed at least one screening. 28,720 (38.2%) of these individuals completed all the FOB tests they were offered and 16,118 (21.4%) completed at least one screening but not all the tests they were offered. 30,415 (40.4%) did not complete any test. Of 893 cancers (20% stage A) diagnosed in screening-group participants (CRC incidence of 1.49 per 1000 person-years), 236 (26.4%) were detected by FOB screening, 249 (27.9%) presented after a negative FOB test or investigation, and 400 (44.8%) presented in non-responders. The incidence of cancer in the control group (856 cases, 11% stage A) was 1.44 per 1000 person-years. Median follow-up was 7.8 years (range 4.5-14.5). 360 people died from CRC in the screening group compared with 420 in the control group-a 15% reduction in cumulative CRC mortality in the screening group (odds ratio=0.85 [95%; CI 0.74-0.98], p = 0.026).

INTERPRETATION

Our findings together with evidence from other trials suggest that consideration should be given to a national programme of FOB screening to reduce CRC mortality in the general population.

Geriatric health maintenance

OBJECTIVE

To highlight articles pertaining to geriatric health maintenance and provide clinicians with current evidence supportive of or opposed to screening or treatment for various diseases and conditions.

METHOD

We conducted a computer-assisted search of the relevant medical literature and summarized the results of pertinent studies in the elderly population.

RESULTS

The geriatric population is progressively increasing in numbers. Unfortunately, no consensus exists about health maintenance in this population. To date, the United States Preventive Services Task Force has made several recommendations about preventive services; however, they did not specifically focus on the geriatric age-group. We outline their guidelines and discuss our clinical practices in a wide variety of encounters with geriatric patients.

CONCLUSION

The efficacy of many screening tests and interventions for preventing illness in elderly patients is unclear. As the general population continues to age, further research in this area will be important.

Haemoccult test properties according to type and number of positive slides in mass screening for colorectal cancer

Despite encouraging results from recent studies, there is still no consensus to undertake mass screening using the Haemoccult test in the general population. The success of mass screening for colorectal cancer depends among other things on Haemoccult test properties. In on-going screening programmes, the Haemoccult test consists of six slides and a test is considered positive if at least one slide is coloured. The aim of this work was to study the influence of the type and number of positive slides on the Haemoccult test's positive predictive value and characteristics of screened lesions. This work focuses on 63,958 first tests in a mass screening programme in Calvados (France) among people aged 45-74 years. There was a linear relation between the positive predictive value for cancer or an adenoma larger than 1 cm and the number of positive slides (P < 10(-4)). The positive predictive value for cancer or large adenoma was significantly higher when 4-6 slides were positive (44.3%) than when only 1-3 were positive (19.1%) (P < 10(-4)). In this latter group, the subjects in whom tumours were detected were younger and had significantly less extensive cancers. Borderline tests (no slides positive and at least one slide with a blue coloration confined to the edges) had a positive predictive value for cancer or an adenoma larger than 1 cm no different to that of tests with 1-3 positive slides. Subjects with borderline results were markedly younger than the others and had less extensive cancers and rectal localisation more often than the others. Our results suggest that (1) increasing the number of positive slides required to declare a test positive leads to an increase in the positive predictive value but is not to be recommended because of the sensitivity of the test and (2) considering borderline Haemoccult tests as positive in on-going and future mass screening campaigns would allow an increase in the sensitivity of the test, especially for rectal cancer and low extensive tumours without any decrease in its positive predictive value.

Flexible sigmoidoscopy plus air-contrast barium enema versus colonoscopy for evaluation of symptomatic patients without evidence of bleeding

One hundred forty-nine patients aged 40 years or more with symptoms suggestive of colonic disease but without evidence of gastrointestinal bleeding (absence of hematochezia, normal serum levels of hemoglobin, and at least one test negative for fecal occult blood) were randomized to undergo either initial colonoscopy or initial flexible sigmoidoscopy plus air-contrast barium enema. Patients with incomplete initial colonoscopy and certain patients with polyps seen on flexible sigmoidoscopy plus barium enema underwent the alternative procedure (barium enema or colonoscopy). The main results were as follows: First, the overall prevalence of cancer in the study was very low (0.67%). Second, initial flexible sigmoidoscopy plus barium enema detected more patients with diverticulosis than did initial colonoscopy (46% versus 31%; p = .01). Initial colonoscopy detected more persons with adenomas (p = .06) than did initial flexible sigmoidoscopy plus barium enema. Patients undergoing initial flexible sigmoidoscopy plus barium enema require the alternative procedure (24%) than were patients undergoing initial colonoscopy (6%; p = .002). Third, sensitivity analyses suggested that for most areas in the United States, initial colonoscopy would be more cost-effective for the outcomes of detection of adenomas and detection of large adenomas, although very few patients in the study had large adenomas. We conclude that the prevalence of colorectal cancer in persons with colonic symptoms but no evidence of bleeding is low and is comparable with the prevalence in an asymptomatic population. Cost-effective selection of imaging strategies in this population can be based on demographic factors such as age and sex, which are better predictors of the presence of adenomas than are symptoms.

Endoscopic and histologic correlates of colorectal polyp bleeding

Until now, the exact mechanism of bleeding from colorectal polyps has not been demonstrated. The present study aimed to identify macroscopic factors and the main source of polyp bleeding. One hundred fifty-seven cases of single colorectal polyp from a variety of clinical situations were investigated to determine whether surface area, shape, color, and location in the colon were correlated with a positive result in the fecal occult blood test. We also searched for the site of bleeding on the surface of polyps under a dissecting microscope and investigated the relationship between bleeding and microerosion and thin surface epithelium on the maximal vertical cross-section of the polyp. The presence of fecal occult blood was found to be correlated with the surface area of colonic polyps. We demonstrated that a red color tone of polyps was caused largely by microerosion and that the area of both microerosion and thin surface epithelium was significantly larger on polyps associated with a positive fecal occult blood test result. The extent of microerosion and thin surface epithelium was found to be correlated with the polyp surface area and villous component. These observations strongly suggest that the area of microerosion and thin surface epithelium tends to increase as the surface area expands, resulting in a higher rate of detection of polyps with malignant potential by the fecal occult blood test.

A simple strategy to improve patient adherence to outpatient fecal occult blood testing

Poor patient adherence reduces the effectiveness of fecal occult blood testing for colon cancer. Patients at the inner-city clinic involved in the study have historically completed only one-third of the tests administered to them. The authors studied three ways of returning test kits (by hand, by mail, and by mail with prepaid postage). Among 146 randomly assigned patients, the completion rates were 37%, 57%, and 71%, respectively. The difference was significant between the first and third groups (p = 0.003), and the cost was less for the third group ($1.71 vs $2.24 per completed test). The authors recommend that clinics serving indigent populations use postage-paid return envelopes with fecal occult blood testing to improve its effectiveness and save money.

Colorectal cancer incidence in pattern and model makers: evidence from a screening program

This study is designed to evaluate the efficacy of colorectal cancer screening in a high risk population of pattern and model makers. The cohort of 1,641 white male automotive pattern and model makers was identified in 1981, and offered colorectal cancer screening. The program involved periodic 60 cm flexible sigmoid examination, stool occult blood testing, and digital rectal examination. Screening was offered in 1981, 1982, 1985, 1988, and 1991. Approximately 60% of those eligible participated in at least one screening examination. Nonparticipants showed a relative risk for incident colorectal cancer of over 10, compared to those who participated at least once in the screening. Cohort tracking has accumulated 10 years; results suggest a benefit to colorectal cancer screening in this population.

Evaluation of new occult blood tests for detection of colorectal neoplasia

BACKGROUND

Hemoccult II, the guaiac-based fecal occult blood test used in most colorectal cancer screening programs, has an unsatisfactory sensitivity for asymptomatic colorectal neoplasms. We evaluated the relative performance of four fecal occult blood tests, directed against various components of the hemoglobin molecule.

METHODS

All tests, Hemoccult II, HemoccultSENSA (a more sensitive guaiac test), HemeSelect (an immunochemical test specific for human hemoglobin), and HemoQuant (the heme-porphyrin assay), were performed by 107 patients with symptomatic colorectal cancer and 81 patients with predominantly asymptomatic adenoma. Hemoccult-SENSA and HemeSelect were performed by 1,355 screenees.

RESULTS

HemeSelect and Hemoccult-SENSA had significantly higher sensitivity for colorectal cancer (97% and 94%, respectively) than the other tests. HemeSelect had the highest sensitivity for adenomas; in 45 patients with large (> or = 10 mm) adenomas, sensitivity was 76% for HemeSelect, 60% for HemoccultSENSA, and 42% for both Hemoccult and HemoQuant. In the screenees, estimated specificity was 97.8% for HemeSelect and 96.1% for Hemoccult-SENSA.

CONCLUSIONS

HemeSelect and Hemoccult-SENSA have the highest levels of sensitivity for detection of colorectal neoplasia, but the immunochemical test HemeSelect provides the best combination of specificity and sensitivity.

Screening strategies for colorectal cancer

The efficacy of screening for colorectal cancer has not been established. Policy-making organizations differ in recommendations for asymptomatic and high-risk groups because of the inadequacy of current evidence. A critical appraisal of the current evidence for screening for colorectal cancer and a discussion of the aims and pitfalls of screening programs are presented.

Colorectal carcinoma: analysis of management in two medical eras

Trends in presentation, diagnosis, management, and outcome were analyzed for 503 patients with colorectal cancer seen at the UCLA Medical Center between 1960 and 1970 (Group A; n = 210) and 1980 and 1985 (Group B; n = 293). Patients in the latter group exhibited a shift in site to the right side of the colon (18% in Group A vs. 31% in Group B; P < .01), an increase in the number of primary resections without colostomy (38% vs. 61%; P < .01), a lower overall complication rate (28% vs. 18%; P = .01), and a decline in 30-day mortality (6.2% vs. 2%; P = .01). Although little difference was seen in detection of asymptomatic tumors, earlier lesions were treated in the latter group, accounting for substantially reduced rate of recurrence (69% in Group A vs. 44% in Group B; P < .01). Future management should include an emphasis on earlier detection in order to continue the trend toward enhanced survival.

Accuracy of colonoscopy for the detection of colorectal polyps

The findings at colonoscopy were compared with the pathologic findings of the surgical specimen in 235 patients who underwent a colon resection for a primary colorectal neoplasm from January 1980 to December 1987 at Roswell Park Cancer Institute. Seven patients (3 percent) were found to have synchronous primary colon carcinomas, and 100 patients (43 percent) were found to have synchronous adenomatous polyps identified by colonoscopy and/or pathology. In patients with polyps 10 mm or greater in diameter, the findings on colonoscopy agreed with the pathology report 96 percent of the time. When polyps of all sizes were included, with many less than 5 mm in diameter, colonoscopy agreed with the pathology in 89 percent of patients. When only the area of the colon resected was used to determine the ability of colonoscopy to locate polyps, 58 percent of polyps of all sizes were located. The majority of the missed polyps were adjacent to a carcinoma. One cecal carcinoma was not seen by colonoscopy because of technical inabilities to reach the cecum. A second carcinoma (20 mm x 17 mm) was not seen at the splenic flexure.

Screening and early diagnosis

Although colorectal cancer is the second leading cause of death in the US, the majority of diagnoses are made at an advanced stage, and screening detects 70% at an early stage, controversy has existed because of a lack of experimental controlled trial evidence showing a decrease in mortality. Indirect and now direct evidence supports the current screening guidelines of the American Cancer Society and the National Cancer Institute as reasonable and should be continued.

Estimates of costs and effects of screening for colorectal cancer in the United States

BACKGROUND

In many ways, colorectal cancer might be an excellent candidate for mass screening because of the following: (1) it is the second leading cause of cancer mortality in the United States; (2) it develops slowly from a precursor lesion; and (3) methods of early detection are available. Barriers to screening include unproven efficacy of the procedure and high costs.

METHODS

Cost analyses are derived from two mathematic models that estimate screening costs and effects based on expert opinion and data from uncontrolled screening studies.

RESULTS

One screening option that follows the guidelines of the American Cancer Society and the National Cancer Institute (annual testing for occult fecal blood and sigmoidoscopy every 5 years) could result in a 40% decrease in colon cancer mortality for American adults between the ages of 50 and 75 years if they comply with screening. This model, developed by David Eddy, projects an average of 44 days of extra life per person screened, at a net cost of $57 per day of life gained. Using assumptions much less favorable to screening, the Office of Technology Assessment modeled this same screening strategy for those aged 65 years and older. This model predicted a similar benefit of extra life per person at a cost of $118 per day of life gained. This doubling of the predicted cost was caused by the inclusion of subsequent colonoscopic surveillance costs for those found to have polyps. Direct costs of screening annually for fecal occult blood and every 5 years by sigmoidoscopy would cost an average of approximately $48 per person per year for screening and follow-up testing of all positive results. Fecal occult blood testing alone, although less effective, costs only $20 per person per year, including follow-up testing of all positive findings.

CONCLUSIONS

The results from randomized trials of fecal occult blood screening will be known in the next 5 years, but trials of screening with sigmoidoscopy will not be complete for 10-15 years. Because mass screening programs will be difficult to fund without better data on their efficacy, colorectal cancer screening will continue to be a matter of individual decision making in the clinical setting for years to come. Clearer presentations of costs and benefits that can be understood by both patients and physicians are needed.

Screening for large bowel neoplasms in individuals with a family history of colorectal cancer

Logistical problems associated with population screening for colorectal cancer are identified and the possibility of targeting screening to those with a familial predisposition to the disease is discussed. Evidence for a substantial genetic effect on the overall incidence of colorectal cancer is reviewed. The screening detection rate of colorectal neoplasms in relatives of patients with colorectal cancer has been shown to be higher than that expected in a non-selected population; the evidence that polypectomy will reduce future colorectal cancer risk in such individuals is explored. Recent advances in the molecular genetics of colorectal cancer susceptibility are reviewed; it is possible that a genetic test might be developed in the future which could identify at least a proportion of those at risk. Excluding financial considerations, the risk-benefit ratio of colonoscopy in a screened population is intimately related to the remaining risk of colorectal cancer in those who undergo the examination. At present, patients undergoing colonoscopy to investigate a positive faecal occult blood (FOB) test as part of a population-based screening programme include individuals with a familial predisposition as well as those without. About 20 per cent of all cases of colorectal cancer are associated with an obvious genetic predisposition, and the risk of cancer in their relatives is high. Because false positives occur with Haemoccult, the residual risk to the population who are FOB positive but do not have a familial trait may be sufficiently low that the dangers of colonoscopy could outweigh the potential benefits. Scotland has a high incidence of colorectal cancer, and analysis of recent Scottish incidence data shows an actuarial lifetime risk of developing this disease of one in 23 for men and one in 33 for women. As a family history of the disease increases that risk by two to four times and the neoplasms arise throughout the colon in such a group, there may be a case for offering colonoscopy to all first-degree relatives of those under 50 years of age at diagnosis, if not of all index cases of colorectal cancer.

Quality of care for colorectal cancer in a fee-for-service and health maintenance organization practice

This study assessed the effectiveness of two types of health plans, offered by the same health care provider, in the diagnosis and treatment of colorectal cancer. Data on 330 cases diagnosed from 1984 through 1989 were abstracted from medical records. Of these, 205 (62%) used fee-for-service (FFS) and 125 (38%) used health maintenance organization (HMO) plans. Overall, there were no differences between FFS and HMO cases for duration of symptoms before diagnosis, training of physician who diagnosed the tumor, anatomic location of the tumor, type of primary treatment, Dukes' stage at final diagnosis, or survival. There were differences between the groups for age, presence of symptoms at diagnosis, time from detection to treatment, and method of detection. Cox regression analysis showed no difference in survival by type of health plan before or after adjusting for age and stage at diagnosis. The findings from this study are consistent with those from studies reporting little or no difference in the process or outcome of care for patients with different types of medical insurance coverage.

Readability and sensitivity of a new faecal occult blood test in a hospital ward environment. Comparison with an established test

OBJECTIVE

To compare the readability and sensitivity of a new guaiac faecal occult blood test, HemoccultSENSA, with those of a standard guaiac-based test, Hemoccult, in a normal working environment.

DESIGN

The two tests were performed in parallel on routine clinical and contrived faecal specimens; those developing the tests were blinded as to the test type.

SETTING

All tests were carried out in the hospital ward environment under normal conditions by nurses working in the ward.

SAMPLES

Fifty faecal samples from healthy volunteer subjects (low concentrations of haemoglobin were added to 40 of these samples) and 145 faecal samples from 65 inpatients likely to have gastrointestinal bleeding.

MAIN OUTCOME MEASURES

Test positivity rate, and graded measures of colour intensity, colour stability and colour pattern.

RESULTS

With patients' samples, the new test gave a greater number of positive results than the standard test (73.1% v. 65.5%; 95% confidence interval of the difference, 3.3%-11.9%). With contrived samples, the blue colour produced during development was more intense (P less than 0.0003), more stable (P less than 0.0025) and covered a larger area (P less than 0.01) with the new test compared with the standard test.

CONCLUSIONS

These results demonstrate the better readability and slightly higher sensitivity of the new test. They justify its use in the ward environment or doctor's office. Patients being tested should consume a low peroxidase diet until the specificity of the new test has been fully evaluated.

The utilization of fecal occult blood testing in the institutionalized elderly

OBJECTIVE

To examine physician use of stool guaiac testing in order to determine indications for testing, how the test was used, and the consequences of a particular test result.

DESIGN

Retrospective case series.

SETTING

Large midwestern inpatient nursing home facility.

PATIENTS

All patients with positive fecal occult blood tests (FOBT) and one-third of patients with negative FOBT.

RESULTS

In an 18-month period, 916 occult blood tests were performed on 339 patients (37% of the nursing home census). Patients over age 90 were as likely to receive FOBT as those under age 70. Fourteen percent of those tested had at least one positive test. Fifty-eight percent of the patients with positive tests underwent no additional diagnostic testing. No cause for the positive FOBT was found for 68% of patients receiving the test for routine screening. Physician estimates of how frequently they employed FOBT for these patients correlated very poorly with their actual practices (r = .17).

CONCLUSION

There is a high prevalence of positive results from FOBT among nursing home patients. In most cases, such results do not cause a change of therapy or result in additional workup. Lack of information on the role of FOBT in nursing home patients contributes to the great diversity in utilization of this test by nursing home physicians.

Single-visit screening and treatment of first-degree relatives. Colon cancer pilot study

A pilot study has been carried out to evaluate three aspects of screening of first-degree relatives of patients with colon cancer in four Hamilton hospitals; yield of adenomas, feasibility of a one-visit approach to screening and treatment, and compliance. Protocol included flexible sigmoidoscopy after full bowel preparation, followed immediately by either therapeutic colonoscopy or diagnostic barium enema, depending on the flexible sigmoidoscopy findings. We found adenomas in 19 percent of 88 first-degree relatives, with a mean age of 52, compared with an expectation of 8 percent. The protocol was found to be acceptable to the relatives and workable for the various groups of physicians in three of four hospitals, despite many initial logistic difficulties. Numerous problems were encountered with compliance of referring physicians, index patients, relatives, and investigating physicians.

Cost-effective management of colon and rectal cancer

Health care costs in the United States of America continue to rise. Legislators, economists and third party payers are becoming increasingly concerned with intervention outcomes and the distribution of resources. It is the responsibility of the medical profession to assume a leading role in assessing the cost-effectiveness of health care interventions. Although many physicians perform informal cost-effectiveness analyses on a daily basis, health economists employ a variety of more complex methodologies. This article will attempt to provide physicians with an understanding of the value and limitations of the tools used in formal cost-effectiveness analyses and demonstrate how these tools may be applied to the management of colon and rectal cancer.

Mass screening for rectal neoplasm in Jiashan County, China

Jiashan county is a rural area in China with very high incidence and mortality rates of colorectal cancer. From 1980 to 1984, we conducted a mass screening for rectal neoplasm in the 11 people's communes in this county. Of the 72,879 individuals who were eligible for screening, 60,496 participated, representing an overall participation rate of 83.0%. Both the fecal occult blood (OB) test and rectoscopy were performed on 47,560 of the participants, and rectoscopy only was performed on the remaining 12,936 individuals. From the mass screening, 15 rectal cancers, 3 carcinoids, 899 polyps, 98 ulcers, and 7 inflammatory tumors were detected, a total of 1022 cases. Eight of the 15 detected cases of rectal cancer were in Dukes' stage A. We did not find any evidence for an association between schistosomiasis and colorectal cancer. Results from the OB test were found to have a negative correlation with results from rectoscopy (odds ratio = 0.8, 95% CI = 0.6, 1.1). The OB test had a high false positive rate of 32.7%, and a poor positive predictive value of 3.5%. Both its positive and negative predictive powers were below 1.0, in other words, its positive likelihood ratio was below 1.0 and negative likelihood ratio was above 1.0, indicating that the OB test is not informative and has a poor predictive accuracy for rectal neoplasm. In addition, there were a number of practical problems concerning the use of the OB test for mass screening in the rural community.(ABSTRACT TRUNCATED AT 250 WORDS)

A critical analysis of the largest reported mass fecal occult blood screening program in the United States

Fecal occult blood testing for the detection of colon cancer remains controversial. We performed a mass screening program from January 24, 1988, to February 19, 1988, with intensive media promotion, including 121 minutes of televised air time. A total of 5,000 primary practitioners were notified by mail. Hemoccult-II tests were distributed to 156,000 individuals; 55,051 (35%) were returned. Ninety-five percent of the respondents were informed of the program by television. A total of 3,375 persons (6%) tested positive for fecal occult blood; of these, 2,469 (73%) informed the center that they saw their physician to initiate a work-up. Information from physicians regarding work-ups was returned on only 1,356 (55%) patients. Diagnostic tests numbered 2,227 (1.6 tests per patient). However, 5% had no testing, 16% had a repeat Hemoccult only, and 35% had neither a barium enema nor colonoscopy performed. Thirty-six colorectal cancers and 212 polyps were identified. The predictive value (i.e., number of cancers per number of patients who tested positive) increased directly by decade. Thirty-three of 36 patients (92%) with cancer underwent either a barium enema or colonoscopy versus only 185 of 438 (42%) patients with a "negative" work-up. Cancers found were carcinoma in situ in 10 patients (29%), Dukes A in 12 (35%), Dukes B in 4 (12%), and Dukes C in 8 (24%); distant metastases were not found in any participant. Thirty-six percent of the tumors were located in either the right or transverse colon. We conclude that: (1) Screening identified early cancers. All were potentially curable and 64% were limited to the bowel wall. (2) Massive Hemoccult distribution was possible over a short interval, but patient and physician compliance was disturbingly low. (3) Total colonic evaluation is mandatory, since at least 36% of tumors were beyond the reach of the flexible sigmoidoscope. (4) Many work-ups were unnecessary (repeat Hemoccults) or inadequate, indicating a need for physician education.

Using ordinal logistic regression to estimate the likelihood of colorectal neoplasia

The utility of ordinal logistic regression in the prediction of colorectal neoplasia was demonstrated in a group of 461 consecutive patients undergoing colonoscopy in a community practice. One hundred twenty-nine patients had adenomatous polyps and 34 had colorectal adenocarcinoma. An ordinal logistic regression model developed in a random subset (292 patients) identified five predictors of colorectal neoplasia. Colorectal neoplasia risk could be predicted using the patient's age, sex, hematocrit, fecal occult blood test result and indication for colonoscopy. The risk of colorectal neoplasia in the remaining subset of patients (169) could be reliably estimated from the model. Ordinal logistic regression analysis in this select group of patients can accurately estimate the likelihood of colorectal neoplasia. Because the generalizability of our findings are unknown, the model should not be applied to other patients. However, application of this technique to an unselected group of patients not already referred for colonoscopy could provide unbiased estimates of colorectal neoplasia risk in individual patients.

Is evaluation of the right colon necessary prior to cecocystoplasty?

Use of the ileocecal bowel segment in urological surgery has become more widespread. Thorough preoperative evaluation of the bowel is seldom performed. A case is presented in which the intraoperative finding of numerous cecal polyps led to abortion of a planned cecocystoplasty. The literature on fecal occult blood testing and screening methods for colorectal neoplasia was reviewed. Patients are classified into 2 categories, average risk and high risk, according to the relative risk for colorectal neoplasia. The data suggest that the fecal occult blood test, if properly performed, is an adequate screening tool for average risk patients. However, because of the high rate of false negative results this test is inadequate for evaluation of high risk patients. It is recommended that such patients should undergo preoperative screening colonoscopy regardless of the fecal occult blood test result.

Is there a preference for different ways of performing faecal occult blood tests?

Low compliance with faecal occult blood screening reduces the power of clinical trials, potential benefit, and efficiency. It has been proposed that the faecal manipulation required to perform conventional guaiac based tests may be an important factor in low compliance. The aim of this study was to evaluate whether use of a new method (vehicle) of stool collection for the faecal occult blood guaiac test would be preferred to the established standard. A novel self-interpreted test, Early Detector (ED), requires the subject to apply a guaiac/peroxide spray to a stool sample collected simply by wiping the anus with a specimen pad. To determine whether this method would be preferred to the stool manipulation required by Haemoccult (HO) and to compare test validity, employees at a London company were invited to use both tests. Eight-hundred and fifty-seven subjects were shown both tests. Before use, 48% indicated a preference for the method of Early Detector; 24% chose Haemoccult (p less than 0.001), while 28% indicated no immediate preference. Seven-hundred and one performed both tests. After use, 74% preferred ED; 5% preferred HO (p less than 0.001); 21% had no preference (NP). The preference for the ED test method was consistent by sex categories, age groups and occupational class. Logistics, aesthetics, and immediacy of results were the main reasons indicated for choosing ED. Whether the preference for ED could result in higher compliance remains to be proven. Its high positivity (14%), however, would preclude its use as a sole test to determine the need for endoscopic and/or radiologic investigation in the screened patient.

Mass screening for colorectal cancer

A voluntary community colorectal cancer screening project to detect occult blood in the stool of asymptomatic individuals was undertaken; 49,353 Hemoccult II kits were distributed. A total of 23,674 completed kits were returned to a central repository and processed (compliance rate, 48 percent); 851 participants had positive results (3.6 percent). Of the 640 who underwent further medical evaluation, 299 participants (46.7 percent) who had adequate follow-up had no evidence of disease. Diverse disease entities were detected in 341 participants, which was 1.4 percent of those enrolled. Forty-one patients (0.17 percent) showed significant findings that included 29 cancers (0.12 percent) and 12 (0.05 percent) noninvasive malignant polyps. Of the cancers, there were 27 colorectal, one non-Hodgkin's lymphoma, and one carcinoma of the vocal cord. In addition, 107 patients (0.45 percent) had benign polyps and 193 patients (0.82 percent) had various diseases of the gastrointestinal tract and other medical conditions. The cost of the program was modest and the results conformed to those found in previous screening surveys. The heightened public awareness of testing for colorectal disease and the detection of early lesions justifies the guaiac test screening program for mass survey.

Role of dietary restriction in Haemoccult screening for colorectal cancer

The aim of this study was to investigate the effect of dietary restrictions on the positivity rate and yield of neoplasia during a study based on Haemoccult screening for colorectal neoplasia. Of 18,925 participants who completed Haemoccult tests on a normal diet, 647 (3.4 per cent) were positive. All repeated the test with dietary restrictions: 251 remained positive and underwent further investigations which revealed 35 carcinomas and 169 adenomas in 129 subjects. The remaining 396 were sent a further Haemoccult test at 3 months. Of these, 317 (80.1 per cent) completed the test: 31 (9.8 per cent) were positive. Further investigation of the 31 positive subjects revealed four carcinomas and 20 adenomas. Retesting with dietary restriction will reduce the false positive rate of Haemoccult when used for colonic cancer screening. However, if the retest is negative a further test should be performed. To minimize the adverse effect this may have on compliance, we have allowed an interval of 3 months to elapse before this retest is requested.

Randomised, controlled trial of faecal occult blood screening for colorectal cancer. Results for first 107,349 subjects

To assess the effectiveness of screening by faecal occult blood tests, 107,349 people without symptoms of colorectal disease identified from general practitioner records have been randomly allocated to test and control groups. 53,464 test subjects were invited to carry out the screening test; 27,651 (53%) of the 52,258 who received the tests did so. Further investigation of the 618 (2.3%) with positive tests showed 63 cancers (52% stage A) and 367 adenomas (266 subjects). Rescreening of subjects with negative results every 2 years (9510 first rescreen, 3639 second) has shown a significant fall in the rate of positive results (1.7% of 7344; 0.3% of 2906). Cancers have also been diagnosed in 20 subjects presenting in the interval between a negative test and rescreening, and in 83 non-responders. The incidence of cancer in the control group (123 subjects; 10.6% stage A) was 0.72 per 1000 person-years. Cancers detected by screening were at a less advanced pathological stage, but it is too early to show any effect of screening on mortality from colorectal cancer.

A retrospective cost-effectiveness analysis of colorectal cancer screening in a public hospital. Savings from reduced hospitalization

We compared the actual diagnosis and treatment costs for nine colon cancer and 19 polyp patients detected by occult blood screening with excess hospitalization costs incurred by a comparable group of traditionally detected patients. Program benefits were calculated from data on group differentials in surgical length of stay, readmissions in the year following surgery, and preventive polypectomies. A sensitivity analysis was performed to evaluate varying estimates of the percentage of polyps that may have become cancers, the urgency of presentation of clinically apparent cancer, and the inclusion or exclusion of the observed differences for hospitalization in the year after surgery. Two year program benefits varied from 59% to 185% of program costs. Adjusting estimates with DRG weightings for resource intensity produced considerably higher benefits. All estimates of program benefits are conservative because screened patients were compared with the 15-20% least severely ill, most favorably staged of all traditionally detected colon cancer patients admitted. Results indicate that occult blood screening programs may produce significant benefits derived from outpatient diagnosis, preventive polypectomies, coordination of care between medical and surgical services, and enhanced patient education.

Screening for colorectal cancer: a critical review

This article discusses the place of symptom detection, endoscopy, and fecal occult blood testing in population screening for colorectal cancer. There is now considerable evidence that screening the population over the age of 50 years for occult blood in the feces will result in an increased yield of tumors localized to the bowel at the time of surgical treatment. These tumors also have other favorable prognostic features and it is likely that the prognosis of this group will be better than the prognosis of patients presenting with symptoms in the usual way. Because of the biases that result from the selection and detection of tumors in screening studies, the mortality results of the control trials now underway must be awaited until it is known whether population screening is of real value. In chemical fecal occult blood screening tests, a compromise has to be made between sensitivity and specificity. The fecal occult blood test most widely used and the one that has been subjected to the most evaluation in screening studies is the guaiac-based slide test, Hemoccult. The predictive value of a positive test for invasive cancer is 11-17%, and for adenomas, 36-41%. This specificity is achieved at a loss of sensitivity, the interval cancer rate reported in screening studies being over 20%. Newly developed immunological techniques appear to be more sensitive and specific, but require further evaluation in population screening studies.

Strategies for screening for colorectal carcinoma

Four tests commonly used in screening strategies to detect colorectal cancer were examined from a cost-effectiveness perspective. Thirteen combinations of the tests were evaluated. Evaluating a positive fecal occult blood test with a double-contrast barium enema study, followed, if necessary, by colonoscopy, is the most cost-effective strategy for individuals at average risk. An alternative screening strategy for higher-risk individuals or for populations in which the frequency of adenomatous polyps is higher is to follow a positive fecal occult blood test directly with colonoscopy. Sensitivity analysis demonstrated that the superior cost-effectiveness of these two strategies compared with the other 11 modeled strategies is almost independent for reasonable alterations in test cost and for the sensitivities and specificities of the procedures. The major contributing factor to the diagnostic cost is the frequency of adenomatous polyps. The major contributing factor to the marginal cost per year of extended life is the frequency of cancer.

Lower gastrointestinal bleeding. A systematic approach to classification and management

Early classification of lower gastrointestinal bleeding as occult, minor overt, or major overt allows a practical approach to evaluation and management. Localization of the bleeding site is the next step. In occult and minor overt bleeding, the cause can usually be determined from results of conventional diagnostic tests; however, angiography and even intraoperative endoscopy may be necessary in some particularly difficult cases. In contrast, major overt bleeding may only allow time for angiographic localization before surgery. Using this approach, the primary care physician can successfully manage most patients with lower gastrointestinal bleeding.

Hemoccult screening for colorectal cancer

A community hemoccult screening project for colorectal cancer resulted in the processing of 18,198 specimens. Positive test results were reported in 3 percent of the total, which ultimately resulted in the identification of 20 colorectal malignancies (0.1 percent) and 53 benign polyps (0.3 percent). The number of malignancies and polyps identified was disappointingly low. Our findings would challenge the concept of unsupervised mass screening from the viewpoint of cost-effectiveness; however, because of the numerous voluntary services and supplies, this particular project was useful in educating the public about early colon cancer detection.

Compliance with fecal occult blood testing: the role of restrictive diets

In this clinical trial, 786 patients screened for colorectal cancer with fecal occult blood testing were assigned to either a "diet" or "no diet" group to examine the effect of advice to restrict intake of red meat and peroxidase-containing vegetables on patient compliance and positivity rates. Restrictive diets did not significantly decrease compliance. Interviews of patients in the "diet" group demonstrated that the majority followed instructions. Positivity rates were similar in the two groups, and clinically significant lesions were found with comparable frequency.