Role of dietary restriction in Haemoccult screening for colorectal cancer

Screen-detected colorectal cancers are associated with an improved outcome compared with stage-matched interval cancers

Background:

Colorectal cancers (CRCs) detected through the NHS Bowel Cancer Screening Programme (BCSP) have been shown to have a more favourable outcome compared to non-screen-detected cancers. The aim was to identify whether this was solely due to the earlier stage shift of these cancers, or whether other factors were involved.

Methods:

A combination of a regional CRC registry (Northern Colorectal Cancer Audit Group) and the BCSP database were used to identify screen-detected and interval cancers (diagnosed after a negative faecal occult blood test, before the next screening round), diagnosed between April 2007 and March 2010, within the North East of England. For each Dukes' stage, patient demographics, tumour characteristics, and survival rates were compared between these two groups.

Results:

Overall, 322 screen-detected cancers were compared against 192 interval cancers. Screen-detected Dukes' C and D CRCs had a superior survival rate compared with interval cancers (P=0.014 and P=0.04, respectively). Cox proportional hazards regression showed that Dukes' stage, tumour location, and diagnostic group (HR 0.45, 95% CI 0.29–0.69, P<0.001 for screen-detected CRCs) were all found to have a significant impact on the survival of patients.

Conclusions:

The improved survival of screen-detected over interval cancers for stages C and D suggest that there may be a biological difference in the cancers in each group. Although lead-time bias may have a role, this may be related to a tumour's propensity to bleed and therefore may reflect detection through current screening tests.

Best practice in primary care pathology: review 8

This eighth best practice review examines four series of common primary care questions in laboratory medicine: (i) sodium abnormalities; (ii) faecal occult blood testing; (iii) warfarin management; and (iv) sputum cytology in diagnosis of bronchopulmonary malignancy. The review is presented in question-answer format, referenced for each question series. The recommendations represent a précis of guidance found using a standardised literature search of national and international guidance notes, consensus statements, health policy documents and evidence-based medicine reviews, supplemented by Medline Embase searches to identify relevant primary research documents. They are not standards but form a guide to be set in the clinical context. Most are consensus rather than evidence-based. They will be updated periodically to take account of new information.

Screening for colorectal cancer--now and the near future

When used appropriately, screening for colorectal cancer (CRC) can reduce disease-related morbidity and mortality. Current methods include fecal occult blood testing (FOBT), flexible sigmoidoscopy [FS], barium enema, and colonoscopy; all are cost-effective techniques. Unfortunately, offering an array of options has not increased screening utilization, which continues to lag behind that of other common cancers. Newer techniques, particularly virtual colonoscopy (VC) and stool DNA testing, may offer attractive alternatives for healthcare provider recommendation and patient use.

An industry based approach to colorectal cancer screening in an asymptomatic population

The uptake of faecal occult blood testing in a workplace based colorectal cancer screening programme was investigated. Altogether 1828 employees aged 41-65 years at a large British industrial company were invited to receive a free faecal occult blood test (Haemoccult). Faecal occult blood tests were completed on three separate days. Patients with positive results were invited to undergo colonoscopy. The number of employees completing kits was measured and differences in compliance according to age, sex, and occupation were tested with a chi2 test. Compliance was 25.4%, and similar in men (25.0%) and women (32.0%, chi2=3.0, not significant). In men, compliance was highest in those aged 51-60 years (30.5% chi2>1.6, p<0.001). Compliance in women aged 41-50 years, 51-60 years, and 61-65 years was similar (Yates's corrected chi2<2.08, not significant). Managers returned more kits than clerical and blue collar workers (28.6% v 23.5%, chi2=5.6, p<0.02). One percent of tests were positive and one patient had a tubular adenoma. Compliance in employees aged 51-60 years was comparable to that achieved in one-off British general practice programmes, but less than that in the large randomised trial of screening in general practices in Nottinghamshire. Health education of large numbers of people is easier at the workplace than in the community. Future screening must target older employees and those with clerical and blue collar jobs.

Screening for colorectal cancer: present, past and future

Colorectal cancer results in 18,000 deaths annually in England and Wales, with 24,000 new cases diagnosed each year. Despite a better understanding of the genetics, and advancement in surgical and anaesthetic techniques, there has been little reduction in mortality and morbidity from this disease over the past 25 years. Colorectal cancer fits recognized criteria for a disease that should be screened in asymptomatic individuals. The putative duration of the adenoma to carcinoma sequence gives an ample window of opportunity to detect and treat colorectal cancer. In this article we have reviewed the strategies involved in screening for colorectal cancer in an asymptomatic population. We have presented trials and arguments for and against the different screening methods and discussed cost effectiveness of screening. In the USA and Canada, major professional organizations and societies now endorse screening; in the UK it is still far from being accepted. We feel that the available evidence shows that colorectal cancer screening has the potential to reduce the morbidity and mortality from this disease and that funding for a mass screening and public education programme should be sought.

Colorectal cancer prevention. An approach to increasing compliance in a faecal occult blood test screening programme

STUDY OBJECTIVE

The assessment of the uptake of colorectal cancer screening offered in a workplace setting.

DESIGN

Employees were offered a free faecal occult blood test (Haemoccult). A repeat letter was sent two months later to non-responders. Those with positive tests were invited for colonoscopy. Compliance was measured according to age, sex, and occupational group and the effects of reinviting non-compliers investigated.

SETTING

Leicester General Hospital, a large university teaching hospital.

PARTICIPANTS

990 employees aged 41 to 65 years.

MAIN RESULTS

Total compliance was 46% with women participating more than men (49% v 34%, chi 2 = 12.2, p < 0.001). The difference was mostly because of women aged 41 to 50 years complying more than their male counterparts (48% v 24%, chi 2 = 15.5, p < 0.0001). Participation was highest in clinical support staff (56%), nurses (52%), and clerical workers (46%). Uptake by doctors (26%) and managers (26%) was significantly lower than by clinical support staff and nurses (chi 2 > 5.5, p < 0.02). Remailing raised compliance slightly from 43.6% to 46.3%. Four employees (1%) had positive faecal occult blood tests but three were negative on repeat testing with dietary restrictions.

CONCLUSIONS

The government favours the development of health promotion programmes as stated in its document "Health at work in the NHS". The response in this study, showed methods to increase compliance must be developed if such programmes are to be successful. As uptake was similar to that in several community based programmes in general practice, workplace based programmes could offer a complementary method of delivering screening.

The effect on compliance of a health education leaflet in colorectal cancer screening in general practice in central England

OBJECTIVE

To raise compliance in a general practice based colorectal cancer screening programme by the use of a simple health educational leaflet.

DESIGN

A randomised controlled trial of the leaflet's effect on completion of faecal occult blood tests. The leaflet explained the high frequency of colorectal cancer, the principles of screening, and addressed reasons for non-compliance.

SETTING

The British town of Market Harborough where most of the population are registered with a single practice.

PARTICIPANTS

These comprised 1571 residents aged 61 to 70 years registered with the practice. Residents were invited to receive a free faecal occult blood test in a colorectal cancer screening programme. Half the population were randomly assigned to receive the educational leaflet about screening.

RESULTS

Compliance in test and control groups, positive rate of stool testing, and pathology detected were measured. Compliance was higher in men who received the leaflet in those aged 61 to 65 years (36% v 27%, chi2 = 4.0, p < 0.05) and in men aged 66 to 70 years (39% v 23%, chi2 = 9.7, p < 0.01). In women, use of the leaflet did not affect compliance in those aged either 61 to 65 years (38% v 36%, chi2 = 0.1, NS) or 66 to 70 years (31% v 31%, chi2 = 0.0, NS). The positive rate of stool testing in patients observing the required dietary restrictions was 1.6%. A significant lesion was detected in 1.4% of people tested (2 carcinomas and 5 patients with adenomatous polyps).

CONCLUSIONS

Health education leaflets addressing reasons for non-compliance significantly increased compliance in men and should be used in screening programmes. Reasons for the lack of success of the leaflet in women should be investigated and other interventions for raising compliance should be developed.

Colorectal cancer screening in asymptomatic populations

Colorectal cancer is the second commonest cause of cancer death in the UK. An effective national screening programme is urgently required to reduce the substantial morbidity and mortality from the disease. The success of any screening programme will depend on the screening test detecting early Dukes's A carcinomas and adenomatous polyps. Prognosis is directly related to tumour staging and a proportion of carcinomas are thought to arise from polyps. Two screening methods exist--faecal occult blood testing and sigmoidoscopy. Large trials of faecal occult blood testing show that it detects more early lesions than in patients presenting with symptoms, but whether this reduces mortality is not yet confirmed and lack of sensitivity for cancers and polyps may ultimately limits its usefulness. The role of sigmoidoscopy in screening, particularly flexible sigmoidoscopy, has not been fully investigated. Flexible sigmoidoscopy has a greater sensitivity for distal lesions than stool testing and a randomised controlled trial of its efficacy is planned in Britain. Compliance with screening is essential to ensure its cost effectiveness in both health and economic terms. Large trials of faecal occult blood testing conducted over several years achieved compliance rates in excess of 60%, although in smaller studies these are often much less. Women frequently participate more than men. There are many reasons for non-compliance including lack of appreciation of the concept of asymptomatic illness and fear of the screening tests and cancer itself. Colorectal cancer screening is relatively cheap compared with breast and cervical cancer screening. Provisional cost estimates suggest that the amount spent to detect or prevent cancer by screening is similar to the amount required to treat a symptomatic patient.

Results of screening, rescreening, and follow-up in a prospective randomized study for detection of colorectal cancer by fecal occult blood testing. Results for 68,308 subjects

All 68,308 inhabitants of Göteborg born between 1918 and 1931 were randomly divided into a test and a control group. The subjects in the test group were invited to perform Hemoccult II fecal occult blood testing on 3 days and to repeat the test after 16 to 24 months. In the prevalence screening 21,347 (63%) performed the test, and in the rescreening 19,991 (60%). Investigation of the 942 (4.4%) with positive tests in the prevalence screening showed 47 cancers and 129 subjects with adenomas > or = 1.0 cm. In the rescreening 5.1% had a positive test, and 34 cancers and 122 subjects with adenomas (> or = 1.0 cm) were found among those. Cancer had also been diagnosed in 19 subjects in the interval between the two screening occasions and in 15 subjects among the non-responders. Forty-four cancers had been diagnosed in the control group during the same period. Cancers detected by screening were at a less advanced stage than in the control group. It is too early to show any effect of screening on mortality from colorectal cancer.

Chemical and immunological testing for faecel occult blood: a comparison of two tests in symptomatic patients

An established chemical faecal occult blood test (Haemoccult prepared without rehydration) has been compared with a new immunological test (Hemeselect) in patients referred for investigation of lower gastro-intestinal symptoms. Hemeselect was shown to have a higher sensitivity for colorectal carcinoma (94.0% compared with 58.0%), the greatest difference in sensitivity between the two tests being for rectal cancers. Similarly Hemeselect was more sensitive than Haemoccult for colorectal adenomas (66.6% vs 33.3%), and for inflammatory bowel disease (88.9% vs 33.3%). However the enhanced sensitivity of Hemeselect for colorectal neoplasia and inflammatory bowel disease was accompanied by a significant increase in the overall rate of positive reactions (32.8% of patients had a positive Hemeselect reaction compared with 14.8% who had a positive Haemoccult test), and a reduction in specificity (84.1% for Hemeselect vs 96.0% for Haemoccult). Hemeselect is a more sensitive indicator of colorectal neoplasia in symptomatic subjects, trials of its use as a screening test for asymptomatic neoplasia appear justified.

Filtering strategies in mass population screening for colorectal cancer: an economic evaluation

On the basis of clinical trial data, 13 strategies for initial screening (filtering) for colorectal cancer are modeled for the purpose of economic evaluation. A wide range of detection cost estimates are generated, although ranking options by detection cost ignores the important consideration of undetected cancers. Formulating the problem as one of cost-effectiveness, however, allows the authors to demonstrate that members of a subset of strategies uniquely outperform all others and that the optimum strategy can be identified by the ex ante specification of the valuation of cancers missed on screening.

Rehydration of guaiac-based faecal occult blood tests in mass screening for colorectal cancer. An economic perspective

Owing to dehydration during storage, faecal occult blood tests have been found to lose sensitivity; accordingly, test rehydration before development has been advocated, although this practice has yet to be subjected to an economic evaluation. In this paper, the results from two major screening trials in Sweden and England, one using rehydration and the other not, are so evaluated, based on a costing model developed within the English trial. The higher sensitivity resulting from rehydration was found to be accompanied by losses in specificity, such that, although more cancers are detected, the costs of screening and of cancer detection are actually considerably higher under the rehydration regimen than with non-hydration.

Value of retesting subjects with a positive Hemoccult in screening for colorectal cancer

Within a prospective randomized screening study for early detection of colorectal cancer with rehydrated Hemoccult II test, the possibility of increasing the specificity of the test by retesting patients with an initially positive Hemoccult II test was investigated. Of those offered the test 3561 (62.6 per cent) returned it and it was positive in 210 cases (5.9 per cent). The repeat test was performed by 184 patients and was positive in 68 (1.9 per cent). All those with a positive initial test had rectosigmoidoscopy to 60 cm and a double contrast enema. A carcinoma was found in one in seven patients with a positive retest but in only one in 100 patients with a negative retest (P less than 0.001). The specificity of the test was, therefore, increased from 95 per cent to 98 per cent and the sensitivity was unchanged. Rescreening was offered at a later date and increased numbers were available: 7147 patients returned the test and 369 (5.2 per cent) were positive. The test was repeated in 360 patients and 118 (1.7 per cent) were positive. A colorectal neoplasm was found in one in three of those with a positive repeat test, compared with one in seven of those with a negative repeat test. In conclusion, screening for early detection of colorectal cancer with a rehydrated Hemoccult II test may be followed by investigation of only those patients with a positive retest. Such a procedure will reduce the work-load by 60 per cent without reducing sensitivity.

Colorectal cancer: implications of mass screening for public health

The faecal occult blood test (FOBT) for colorectal cancer has a place in clinical practice in case finding, and, perhaps, in screening high-risk groups, but is it a worthwhile screening test when applied to the general population? This question is important and topical: there is increasing interest in Australia in screening by FOBT, but such a programme would be neither free of risk, nor inexpensive. We argue that there is not yet satisfactory evidence that screening by FOBT reduces mortality from colorectal cancer. There is no quicker way of learning whether FOBT saves lives than to wait for the results of the major overseas trials, the first of which should become available in the next three to five years. Until this evidence becomes available, Australia should not proceed with mass screening for colorectal cancer by FOBT. Sporadic and haphazard screening should be discouraged. What we can, and should, do now is find out more about the attitudes and behaviour of consumers and providers of screening by FOBT, the infrastructure that would be required to promote and sustain an effective mass screening programme, the total costs of colorectal cancer screening, and the performance in representative populations of new screening technologies.

Screening an asymptomatic population for colorectal cancer

The best prospect of realizing a reduction in mortality from colorectal cancer appears to be by presymptomatic detection in a screened population. Presently, the only feasible method of mass population screening is by the detection of faecal occult blood and it is encouraging that all the major trials demonstrate that asymptomatic malignancy may be detected in this way. Furthermore, the screen-detected cancers are generally at an earlier pathological stage than those appearing in control populations. However, a note of caution is required. At the present time it is too early to demonstrate a reduction in mortality from the disease and there is evidence of a length bias, with more of the screen-detected cancers being well differentiated. The results of the large controlled trials will enable the benefits of screening to be viewed objectively and a recommendation for, or against, screening to be made.