Mass screening for colorectal cancer by occult blood testing under restricted diet

We conducted a mass screening survey for colorectal cancer by the combination of fecal occult blood tests under a restricted diet and a medical questionnaire in 7,392 healthy volunteers. Further diagnostic work-up was needed in 1,934 (26.2%) individuals. Of these, 1,409 (72.9%) showed occult blood in at least one slide, 245 (12.7%) had symptoms and 306 (15.8%) had a positive family history. Proctosigmoidoscopy, barium enema and flexible colonoscopy were performed in 1,251, 779 and 95 persons, respectively. Colorectal cancers were detected in 10 individuals (0.14%); 5 of these were in the early stage.     

Mass screening for colorectal cancer by testing fecal occult blood

The validity of screening for colorectal cancer by testing for occult blood on 2 successive days was evaluated over a 2-year period beginning April 1980 by testing 9449 individuals without symptoms. The Shionogi slide (Shionogi Pharmaceutical Co., Osaka, Japan), a commercial guaiac-impregnated slide with moderate sensitivity, was used for screening subjects under dietary restriction. Of the 1401 persons (14.8%) who had a positive reaction for occult blood, 858 (61.2%) received further diagnostic examinations, and 265 of them proved to have one or more abnormalities of the gastrointestinal tract. Colorectal cancer was detected in 11 persons and polyps in 91 persons. Eight of the cancers were in an early stage. This screening method was found to be suitable for large-scale mass screening, and appears to have high diagnostic value.     

Fecal occult blood testing for colorectal cancer: a perspective.

Colorectal cancer is an important health problem in western countries. Early detection of colorectal cancer reduces mortality. The best evidence for the effectiveness of screening for colorectal cancer is with annual or biennial fecal occult blood testing. While the benefit of fecal occult blood testing is small in absolute terms, the incremental cost-effectiveness of this screening strategy appears acceptable. Combining fecal occult blood testing with periodic flexible sigmoidoscopy or replacing it altogether with infrequent colonoscopy are theoretically attractive screening strategies, but the incremental costs and effectiveness of these more intensive screening strategies have not been well defined. Whether and how to implement population-based screening for colorectal cancer depends largely on available resources.     

Fecal occult blood test and mass screening for colorectal cancer

It has become promising to establish a method for mass screening of colorectal cancer through the development of immunological fecal occult blood test. It has been shown that such tests have higher specificity and sensitivity compared to conventional chemical tests not only in cancer subjects and normal controls but in population screening trials. Further study is required to decide the optimal system within the framework of the screening such as the number of specimens, target age, and screening interval, etc. The efficacy of fecal occult blood screening remains to be shown in spite of the several randomized controlled trials completed or on-going. However, a case control study has strongly suggested that such screening would reduce the mortality from colorectal cancer.     

Debate on colorectal cancer screening by faecal occult blood.

We read with great interest the debate on colorectal cancer(CRC) screening in volume 13 issue 1 of the Annals of Oncology[1]. As opinions in the debate are controversial we would liketo contribute to the discussion on the basis of our experience. The criticisms by the majority of the authors involved in thedebate are based on the results of randomised trials that demonstratethe efficacy of guaiac-based faecal occult blood tests (FOBTs).Guaiac testing was the only available method at the time thosetrials started, approximately two decades     

Evaluation of the optimum cut-off point in immunochemical occult blood testing in screening for colorectal cancer

This study was carried out to assess, from the aspects of cost-effectiveness and diagnostic validity, the optimum cut-off point for immunochemical occult blood testing using a 2-day method as a means of screening for colorectal cancer. Four thousand, two hundred and sixty asymptomatic individuals were subjects of this study. They gave samples for an immunochemical fecal occult blood test, and colonoscopy was carried out during a medical check-up. For evaluation of the optimum cut-off point, three cut-off levels of fecal haemoglobin, 50, 150 and 300 ng/ml, were used. A total of 27 patients with colorectal cancer were diagnosed. The average costs to detect one patient with colorectal cancer and the sensitivity and specificity of these three cut-off points of fecal haemoglobin were evaluated. The average costs for the detection of one cancer case were calculated as $2870.45 for cut-off level of 50 ng/ml, $2492.98 for that of 150 ng/ml and $3329.09 for that of 300 ng/ml, respectively. The sensitivity and specificity were calculated as 89 and 94% for the 50 ng/ml cut-off level, 81% and 96% for the 150 ng/ml cut-off level and 56 and 97% for the 300 ng/ml cut-off level, respectively, indicating a significant difference in the sensitivity between the 50 and 300 ng/ml levels (P<0.05), as well as between the 150 and 300 ng/ml levels (P<0.05), and a significant difference in the specificity between the 50 and 300 ng/ml levels (P<0.05). However, no significant difference was observed in the specificity between the 50 and 150 ng/ml levels. The findings show that 150 ng/ml of fecal haemoglobin is the optimal cut-off point when carrying out the OC-Hemodia test as a means of screening for colorectal cancer.     

Effect of rehydration on guaiac-based faecal occult blood testing in colorectal cancer screening.

Screening for colorectal cancer by means of unhydrated Hemoccult (HO) is in progress in the Province of Florence since 1982. In 1990 rehydrated HO was introduced in the town of Empoli. Five adjacent municipalities where screening had started in 1987 were selected for comparison. In both areas subjects aged 40-70 were invited by mail to undergo the screening protocol. HO-positive subjects were invited to undergo either pancolonoscopy or a combination of left colonoscopy and double contrast barium enema. HO-negative subjects were invited to repeat screening 2 years later. The positivity rate of HO was significantly higher (P < 0.001) for rehydrated (5%) as compared to unhydrated (3.1%) HO. The positive predictive values for cancer (unhydrated: 5.8%; rehydrated: 8.9%) and for adenomas (unhydrated: 26.7%; rehydrated: 25.5%) did not significantly differ. The detection rates of rehydrated HO were significantly higher as compared to unhydrated HO both for cancer (0.37% vs 0.15%; P < 0.05) and adenomas (1.06% vs 0.72%; P < 0.05%). In the present experience rehydration doesn''t produce any decrease in the positive predictive value for cancer or adenomas and the increase in the positivity rate appears quite acceptable when considering the significant increase in the detection rates of cancer and adenomas. We conclude that rehydrated HO should be introduced as the standard test for screening in order to increase sensitivity for colorectal cancer and adenomas.     

Fecal occult blood screening for colorectal cancer: open issues.

Data from seven case-control and--mainly--three randomized clinical trials consistently indicate that biennial fecal occult blood screening (FOBT) can reduce colorectal cancer (CRC) mortality by approximately 20% after 10-18 years. The reduction may be greater in compliant subjects. In the long-term, incidence also appears to be reduced. There are suggestions that the effect of annual screening may be greater, although data are inadequate to quantify the potential advantages of annual versus biennial screening. The issue of the effectiveness of FOBT in the general population and, more important, of comparative cost-effectiveness with other possible screening tests for CRC, however, remain open to discussion.     

Advantage of immunochemical fecal occult blood test in screening for colorectal cancer

Colorectal cancer screening is a high public health priority in all industrialized countries. However, the low sensitivity of the common guaiac screening test (Haemoccult II) makes practitioners and public health deciders reluctant to set up national screening program. In recent years, immunochemical tests based on the use of a specific antibody have been found to be more sensitive than the Haemoccult II test. However, for screening purposes, any gain in sensitivity is of interest only if specificity and positive predictive value are satisfactory. As instance, rehydration of the Haemoccult II test prior to lecture can increase sensitivity, but the associated decrease in specificity and positivity predictive value and the high positivity rate render its value in mass screening debatable. Moreover, extra costs, if existing, must be acceptable for the society. Until recently, immunochemical tests costs made it unaffordable in our societies. The arrival of automated reading is likely to remove this obstacle. Moreover it offers the opportunity of positivity cut-off choice. A recent study was conducted in Cotentin (France) to assess the performance of an immunochemical test with an automated reading technique (Magstream 1000) for different haemoglobin content cut-off points. As previous American, Japanese, Chinese and Italian studies, this study suggests that the use of immunochemical tests could lead a substantial gain, in screening sensitivity. Moreover by choosing a higher haemoglobin content as cut-off point (50 ng/ml instead of usual cut-off at 20 ng/ml), a gain in sensitivity can be obtained with a satisfactory specificity (97%) and positivity rate (3%). Considering the increasing number of publications, the use of an immunochemical test with an automated reading technique could improve the prospects for mass-screening for colorectal cancer, since it offers a promising alternative to guaiac tests.     

Guaiac and immunochemical tests for faecal occult blood in colorectal cancer screening.

Seven hundred and eighty-six subjects spontaneously referring to our Center performed two guaiac (Rehydrated Hemoccult II (R.HO), and Hemoccult Sensa (HO S.)), and two immunochemical (OC Hemodia (Hdia) and Hemeselect (Hsel)) faecal occult blood tests on three consecutive faecal determinations. The positivity rates of 3 day R.HO, HO S., Hdia, and Hsel were 4.8%, 5.6%, 8.4% and 11.2% respectively. One hundred and thirty-five of the 150 subjects with at least one positive test completed the diagnostic work-up. Cancer was detected in three subjects and adenomas in 15. Three-day specificity estimates of R.HO, HO S., Hdia and Hsel in the overall series were 96.1%, 96.0%, 93.8% and 91.2% respectively, the differences between guaiac and immunochemical tests being significant. Corresponding values of specificity as determined on the first faecal sample only in the overall series were 98.1%, 98.3%, 96.1% and 94.9% respectively. No significant difference in specificity is evident when 3-day guaiac tests are compared to 1-day immunochemical ones. Three-day immunochemical testing is not recommended for screening purposes due to its very low specificity. Nevertheless, 1-day immunochemical testing is almost as specific as 3-day guaiac testing. A preliminary estimate of colonic neoplasms detection rates shows no difference as well. The benefit of 1-day testing on screening acceptability is evident, but the impact on sensitivity should be evaluated in a screening situation with a proper study design and a larger sample size.     

反向被动血凝法检测粪便潜血对大肠癌人群筛检的效果评价

Evaluation of reverse passive hemagglutination (RPHA) fecal occult blood (FOB) test in screening for colorectal cancer was carried out in a group of subjects (3034 persons) with history of rectal polyp and ulcer. All subjects were examined by 60 cm fiberoptic colonoscopy, RPHA and benzidine (BT) FOB tests. Among this high risk population, 10 cases of colorectal cancer and 1 case of rectal carcinoid were detected by colonoscopy and pathology. Regarding the findings under fiberoptic colonoscopy as a reference standard, the sensitivity of RPHA and BT in screening for colorectal cancer was 63.6% and 72.7%; the specificity was 81.9% and 61.7%; the general indicator--Youden index was 0.46 and 0.34, respectively. In 7 cases of colorectal cancer with both FOB tests positive, 5 (71%) had lesions in early stages (Dukes A and B). The results indicate that comparing with BT, RPHA has slightly lower sensitivity but higher specificity. RPHA fecal occult blood test could be used as preliminary screening for colorectal cancer.     

Colorectal cancer screening by fecal occult blood testing: results of a population-based experience

AIMS AND BACKGROUND: The study evaluated the results of an experimental screening protocol for colorectal cancer by fecal occult blood testing in a municipality of the Province of Florence. METHODS: A total of 15,235 subjects aged 50-70 years were invited to perform a 1-day immunochemical fecal occult blood testing without any dietary restrictions. All eligible subjects were sent a personal invitation letter, followed by a postal reminder to non-responders. Subjects with a negative stool test were advised to repeat screening after 2 years. Subjects with a positive screening test were invited to undergo full colonoscopy or a combination of left colonoscopy and a double contrast barium enema. RESULTS: A total of 6,418 subjects performed the screening test, with an overall compliance of 42.1%. A total of 268 compliers had positive test results. The positivity rate was 4.2%. Detection rate for cancer and for adenomas was 5.1% and 11.6%, respectively. The positive predictive value was 14.3% for cancer and 32.5% for adenoma. A higher compliance was recorded in subjects born in the province of Florence or living in the centre of the town, in married subjects, and in women. The best results in compliance were associated with the direct distribution of fecal occult blood testing kits by general practitioners to their outpatients. CONCLUSIONS: The study provides useful information about the efficiency and feasibility of a screening program for colorectal cancer using fecal occult blood testing. Compliance results confirm the importance of GP involvement in oncological screening.     

Cost-effectiveness of population-based screening for colorectal cancer: a comparison of guaiac-based faecal occult blood testing, faecal immunochemical testing and flexible sigmoidoscopy

Background:

Several colorectal cancer-screening tests are available, but it is uncertain which provides the best balance of risks and benefits within a screening programme. We evaluated cost-effectiveness of a population-based screening programme in Ireland based on (i) biennial guaiac-based faecal occult blood testing (gFOBT) at ages 55–74, with reflex faecal immunochemical testing (FIT); (ii) biennial FIT at ages 55–74; and (iii) once-only flexible sigmoidoscopy (FSIG) at age 60.

Methods:

A state-transition model was used to estimate costs and outcomes for each screening scenario vs no screening. A third party payer perspective was adopted. Probabilistic sensitivity analyses were undertaken.

Results:

All scenarios would be considered highly cost-effective compared with no screening. The lowest incremental cost-effectiveness ratio (ICER vs no screening €589 per quality-adjusted life-year (QALY) gained) was found for FSIG, followed by FIT (€1696) and gFOBT (€4428); gFOBT was dominated. Compared with FSIG, FIT was associated with greater gains in QALYs and reductions in lifetime cancer incidence and mortality, but was more costly, required considerably more colonoscopies and resulted in more complications. Results were robust to variations in parameter estimates.

Conclusion:

Population-based screening based on FIT is expected to result in greater health gains than a policy of gFOBT (with reflex FIT) or once-only FSIG, but would require significantly more colonoscopy resources and result in more individuals experiencing adverse effects. Weighing these advantages and disadvantages presents a considerable challenge to policy makers.     

Population colorectal cancer screening with fecal occult blood test.

Screening for early detection of colorectal cancer using fecal occult blood testing has been shown to be effective in reducing mortality from this disease. The largest Health Maintenance Organization in Israel initiated the use of Hemoccult Sensa in 1992 to evaluate the field performance of this test. All primary care physicians were invited to order home-based tests for their asymptomatic patients 50-74 years of age. This report summarizes the results of 45,166 tests performed, 22,193 in the prevalence round. Seventy-eight cancers, 60 patients with adenomas, and 163 patients with polyps were detected, yielding a cancer detection rate of 2.61/1,000 screened in the prevalence round. Of these, 21.6% were in the right colon. Of screen-detected cancers, 44.5% and 58.9% were detected in Dukes' A and in situ stages in the prevalence and incidence rounds, correspondingly. The overall estimated sensitivity of the test (median follow-up, 35 months) was 85.3% for the prevalence round with a specificity of 95.5%. The sensitivity for left-side tumors (87.9%) was higher than for right-side or rectal tumors (78.6%). The positive predictive value for cancer increased with increasing number of positive fields. Four or more positive fields had a positive predictive value for cancer of 16-26% and a positive predictive value of 46-71% for all tumors combined. Population screening with a sensitive fecal occult blood test performs well outside a trial setting, detecting a high proportion of expected tumors with favorable stage distribution. Given its proven power to significantly reduce mortality, use of this test is strongly advised to both medical organizations and the healthy population at average risk.