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Summary

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Patient population
  6. Hemoccult SENSA
  7. FlexSure OBT
  8. Correlation with clinical findings
  9. Statistical analysis
  10. Results
  11. Test sensitivity for colorectal cancer ()
  12. Test sensitivity for significant colorectal neoplasia ()
  13. Combined approach (Hemoccult SENSA plus FlexSure OBT)
  14. Discussion
  15. Acknowledgements
  16. References

Background : Colorectal cancer screening by guaiac faecal occult blood test has been shown to reduce the incidence and mortality of colorectal cancer in Western populations. The optimal faecal occult blood test, whether guaiac or immunochemical, for colorectal cancer screening in the Chinese population remains to be defined.

Aim : To compare the performance characteristics of a sensitive guaiac-based faecal occult blood test (Hemoccult SENSA) and an immunochemical faecal occult blood test (FlexSure OBT) in a Chinese population referred for colonoscopy.

Methods : One hundred and thirty-five consecutive patients who were referred for colonoscopy and who met the study inclusion criteria took samples for the two faecal occult blood tests simultaneously from three successive stool specimens, with no dietary restrictions. All tests were developed and interpreted by a single experienced technician who was blind to the clinical diagnosis. The sensitivity, specificity and positive predictive value for the detection of colorectal adenomas and cancers were estimated for the two tests.

Results : The sensitivity, specificity and positive predictive value for the detection of significant colorectal neoplasia (adenomas ≥ 1.0 cm and cancers) were 91%, 70% and 18% for Hemoccult SENSA and 82%, 94% and 47% for FlexSure OBT. The specificity and positive predictive value were significantly higher for FlexSure OBT than for Hemoccult SENSA (P < 0.001 and P = 0.016, respectively). Combining the positive results from both faecal occult blood tests did not improve the accuracy.

Conclusion : The positive predictive value of the immunochemical faecal occult blood test for the detection of significant colorectal neoplasia was 29% better than that of the sensitive guaiac-based test. This may relate to the Chinese diet and requires further study. The poor specificity of the sensitive guaiac-based test, without dietary restriction, makes it less useful for colorectal cancer screening in a Chinese population.


Introduction

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Patient population
  6. Hemoccult SENSA
  7. FlexSure OBT
  8. Correlation with clinical findings
  9. Statistical analysis
  10. Results
  11. Test sensitivity for colorectal cancer ()
  12. Test sensitivity for significant colorectal neoplasia ()
  13. Combined approach (Hemoccult SENSA plus FlexSure OBT)
  14. Discussion
  15. Acknowledgements
  16. References

Colorectal cancer is a leading cause of cancer mortality in many Western countries. This is also true for Singapore, Malaysia and certain parts of southern China, such as Hong Kong.1 For this reason, colorectal cancer is rapidly becoming a major medical and economic burden in China. Patients with colorectal cancer are often asymptomatic until the cancer is advanced, and the survival rate from colorectal cancer is directly related to the stage at diagnosis. It is believed that most cases of sporadic colorectal cancer arise from pre-existing adenomatous polyps. By screening asymptomatic, average-risk individuals, curable cancers or removable adenomatous polyps can be detected, thereby interrupting the natural history of the disease or increasing the chance of cure.2

Colorectal cancer screening of asymptomatic individuals with faecal occult blood tests has been shown to improve the survival of patients.3–6 Three large-scale randomized trials (USA, UK and Denmark), using a guaiac-based faecal occult blood test (Hemoccult), reported mortality reduction from colorectal cancer of 15–33% on an intention-to-screen basis.4–6 These trials also demonstrated that, when screening was repeated annually or biennially, an even higher level of sensitivity was achieved (i.e. the programme sensitivity for the detection of colorectal neoplasia at a treatable stage was improved with each screening cycle). Furthermore, screening can also reduce the incidence of colorectal cancer through the identification and removal of large adenomatous polyps.7

In Hong Kong, the incidence of colorectal cancer has increased significantly over the past decade, and it is now the second most common cancer after lung cancer. In 1997, the age-standardized rates of colorectal cancer per 100 000 males and females were 38.1 and 27.4, respectively.8 These rates are comparable with the age-standardized rates per 100 000 white males in the USA (43.9), Japan (39.5) and Australia/New Zealand (45.8).9, 10 Colorectal cancer is becoming a major medical problem in Hong Kong, as well as in the industrialized, westernized populations of China.11

The faecal occult blood test is the simplest non-invasive colorectal cancer screening method available. There are basically two types of faecal occult blood test commercially available: guaiac tests that detect the pseudoperoxidase activity of haem, and immunochemical tests that detect the globin protein of human haemoglobin. Hemoccult SENSA, compared with the more commonly used Hemoccult II, is a sensitive guaiac test with an enhancer in the developer that allows for the detection of lower levels of peroxidase activity than those detected by Hemoccult II.12 Guaiac tests require the avoidance of large amounts of red meat and certain uncooked vegetables, vitamin C and non-steroidal anti-inflammatory drugs (NSAIDs) before and during the faecal sample collection period.13 As diet and the use of certain medicines (e.g. aspirin) can vary widely between different populations, these requirements can have a significant effect on patient compliance and the accuracy of the tests and require careful evaluation in any target population. Previous experience with Hemoccult SENSA in Western populations has shown that most dietary limitations can be eliminated by waiting for 3 days before faecal occult blood test development.14–16 In contrast, immunochemical tests do not require specific dietary restriction, but their costs are higher.

Little experience has been obtained on the use of the sensitive guaiac faecal occult blood test in non-Western populations, and it is assumed that it will be difficult for the Chinese population to comply with the dietary restrictions required for the sensitive guaiac-based test. Thus, we performed an endoscopically controlled evaluation of the faecal occult blood test by comparing Hemoccult SENSA with an immunochemical test (FlexSure OBT), with no dietary limitations, in a Chinese population.

Patient population

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Patient population
  6. Hemoccult SENSA
  7. FlexSure OBT
  8. Correlation with clinical findings
  9. Statistical analysis
  10. Results
  11. Test sensitivity for colorectal cancer ()
  12. Test sensitivity for significant colorectal neoplasia ()
  13. Combined approach (Hemoccult SENSA plus FlexSure OBT)
  14. Discussion
  15. Acknowledgements
  16. References

Between October 2000 and May 2001, 136 consecutive patients at Queen Mary Hospital, Hong Kong, who required colonoscopy for the investigation of gastrointestinal symptoms or colonic polyp surveillance, were recruited. One patient had the test developed 19 days after collection and was excluded from the analysis. Patients with a previously positive faecal occult blood test, history of overt gastrointestinal bleeding, active rectal bleeding, menstruation, haematuria and known inflammatory bowel disease were excluded. Patients were asked to start faecal sampling for the faecal occult blood tests at least 5 days before hospital admission to ensure that three samples were collected before bowel preparation commenced. For this study, no dietary restriction was requested. Medications, such as vitamin C supplements, aspirin and NSAIDs, were withdrawn 1 week before preparation of the stool tests.

Patients were asked to prepare faecal samples from each stool for the two faecal occult blood test kits: Hemoccult SENSA and FlexSure OBT. Both tests were supplied by Beckman Coulter, Inc., Fullerton, CA, USA. Subjects prepared samples from three consecutive stools according to the manufacturer's instructions, sampling from two different areas on the surface of each stool. To keep the stool sample dry during collection, patients were provided with a disposable paper stool collection device that was placed on the toilet seat. Hemoccult SENSA triple cards have two windows on each of the three-sample collection cards; samples were taken with a wooden applicator from two different parts of the stool and smeared on two windows of the Hemoccult SENSA test card for three sequential stools. In the case of FlexSure OBT, the collection card was similar in appearance and preparation to Hemoccult SENSA, but samples were taken with a wooden applicator from two different parts of the stool and mixed together on the two windows (upper and lower) of the FlexSure OBT sample collection card. The same medical interviewer who provided the patients with instructions distributed all faecal occult blood tests. Test cards were kept in a cool place until all three samples had been collected and were returned before or on the day of colonoscopy. All tests were developed and interpreted by a single experienced technician who was blind to the clinical diagnosis.

Hemoccult SENSA

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Patient population
  6. Hemoccult SENSA
  7. FlexSure OBT
  8. Correlation with clinical findings
  9. Statistical analysis
  10. Results
  11. Test sensitivity for colorectal cancer ()
  12. Test sensitivity for significant colorectal neoplasia ()
  13. Combined approach (Hemoccult SENSA plus FlexSure OBT)
  14. Discussion
  15. Acknowledgements
  16. References

The principle of the Hemoccult SENSA test is the oxidation of guaiac by hydrogen peroxide to a blue-coloured compound in the presence of haem. The haem portion of haemoglobin catalyses the oxidation of α-guaiaconic acid (active component of guaiac) by hydrogen peroxide (active component of the developer) to form a highly conjugated blue quinone compound. Hemoccult SENSA contains an enhancer, which allows for the detection of lower levels of peroxidase activity. This enhancer, according to the manufacturer, produces a more stable and readable positive result than Hemoccult II. The Hemoccult SENSA test was developed according to the manufacturer's instructions, no sooner than 3 days after all three samples had been collected, but no later than 14 days after the first sample had been collected. Hemoccult SENSA tests were developed by applying two drops of developer to each window, and then observed for 1 min. One drop of developer was applied to the control (Performance Monitor) area on each card, and the result was read within 10 s. Any blue colour on one or more test windows (six windows) was interpreted as a positive result for the patient.

FlexSure OBT

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Patient population
  6. Hemoccult SENSA
  7. FlexSure OBT
  8. Correlation with clinical findings
  9. Statistical analysis
  10. Results
  11. Test sensitivity for colorectal cancer ()
  12. Test sensitivity for significant colorectal neoplasia ()
  13. Combined approach (Hemoccult SENSA plus FlexSure OBT)
  14. Discussion
  15. Acknowledgements
  16. References

FlexSure OBT employs the principle of lateral flow immunochromatography to detect human haemoglobin in faecal samples. In the laboratory, the tab of each sample collection card was removed and placed on the developing pad of the FlexSure OBT test development card (a separate card). The sample pad and tab were hydrated with three drops of buffer and the card was closed to initiate flow. As the sample flowed down the test strip, it hydrated the colloidal gold antihuman haemoglobin antibody conjugate, and, if haemoglobin was present in the sample, a haemoglobin–conjugate immune complex was formed. The complex was captured on the test strip, in a zone containing antihuman haemoglobin antibodies, to form a visible pink test line. Unbound conjugate continued to flow down the test strip and was bound on the control line, which contained conjugate-specific antibodies. According to the manufacturer's instructions, all tests were read at 5 min. The test was positive if two pink lines appeared in the reading window. If one test line appeared in the control area, the test was negative. A test was invalid if the control line did not appear.

Correlation with clinical findings

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Patient population
  6. Hemoccult SENSA
  7. FlexSure OBT
  8. Correlation with clinical findings
  9. Statistical analysis
  10. Results
  11. Test sensitivity for colorectal cancer ()
  12. Test sensitivity for significant colorectal neoplasia ()
  13. Combined approach (Hemoccult SENSA plus FlexSure OBT)
  14. Discussion
  15. Acknowledgements
  16. References

Colonoscopy was performed without a knowledge of the faecal occult blood test results. If colorectal polyps were detected, the polyp site was recorded and polypectomy was performed. Polyps were examined histologically and the size of each polyp and its histological type were noted. The location of cancers and their histology were also recorded. Colonoscopy was incomplete in two patients (1.5%) due to an obstructing tumour at the transverse colon and rectum, respectively.

Statistical analysis

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Patient population
  6. Hemoccult SENSA
  7. FlexSure OBT
  8. Correlation with clinical findings
  9. Statistical analysis
  10. Results
  11. Test sensitivity for colorectal cancer ()
  12. Test sensitivity for significant colorectal neoplasia ()
  13. Combined approach (Hemoccult SENSA plus FlexSure OBT)
  14. Discussion
  15. Acknowledgements
  16. References

The presence of an adenomatous polyp of any size or cancer was considered as a positive finding on colonoscopy. Patients were classified by their largest adenoma detected or the presence of cancer. The findings were further analysed according to clinically significant neoplasia (adenomas ≥ 1.0 cm in diameter plus cancers). The sensitivity, specificity and positive predictive values of the two faecal occult blood tests were calculated. To evaluate whether a combination of the Hemoccult SENSA and FlexSure OBT results could further improve the accuracy, the approach suggested by Allison et al.17 was examined. In this approach, the result for an individual was considered to be positive if, given a positive Hemoccult SENSA, FlexSure OBT was also positive. If the Hemoccult SENSA result was negative, the combined result was interpreted as negative regardless of the FlexSure OBT result. The statistical methods used included Student's t-test, chi-squared test and Fisher's exact test, and differences were estimated by comparing the confidence intervals of paired tests. A P value of < 0.05 was considered to be statistically significant.

Results

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Patient population
  6. Hemoccult SENSA
  7. FlexSure OBT
  8. Correlation with clinical findings
  9. Statistical analysis
  10. Results
  11. Test sensitivity for colorectal cancer ()
  12. Test sensitivity for significant colorectal neoplasia ()
  13. Combined approach (Hemoccult SENSA plus FlexSure OBT)
  14. Discussion
  15. Acknowledgements
  16. References

All the study patients were ethnic Chinese with a mean age of 58 years (range, 38–90 years) and 58% were female. Twenty patients (15%) had a family history of colorectal neoplasia. Thirty-eight patients (28%) had a personal history of colonic polyps and 15 (11%) had a personal history of colorectal cancer. The indications for the remaining patients were abdominal pain (n = 15, 11%), iron deficiency anaemia (n = 17, 13%) and alteration of bowel habit (n = 30, 22%).

Ninety-nine patients (73%) had a normal colonoscopy examination. Twenty-three patients were found to have adenomatous polyps (two had adenomas ≥ 1.0 cm) and nine had colorectal cancer. Two of the nine patients with colorectal cancer had obstructing lesions that prevented a complete colonoscopic examination. Overall, Hemoccult SENSA and FlexSure OBT positivity rates were 41% (56/135) and 14% (19/135), respectively (Table 1). Both tests had a mean time before development of 6.8 days (range, 3–14 days) from the first day of collection. The mean time before development was similar between faecal occult blood tests with positive results and those with negative results.

Table 1.  Positivity rates of the Hemoccult SENSA (HOS) and FlexSure OBT (FS) tests for the detection of colorectal cancer, adenoma and significant colorectal neoplasia (cancer and adenomas ≥ 1 cm) using colonoscopy as the gold standard
End-point or subject settingHOS (%)FS (%)P value
  1. PPV, positive predictive value.

Overall positivity rate (n = 135)56/135 (41)19/135 (14)< 0.0001
Positivity in normal colon (n = 100)30/99 (30)6/99 (6)< 0.001
Cancers detected9/9 (100)8/9 (89)
Large adenomas detected1/2 (50)1/2 (50)1.0
Significant neoplasia detected10/11 (91)9/11 (82)1.0
PPV for cancers9/56 (16)8/19 (42)0.028
PPV for significant neoplasia10/56 (18)9/19 (47)0.016
Significant neoplasia detected above splenic flexure4/4 (100)4/4 (100)1.0
Significant neoplasia detected below splenic flexure6/7 (86)5/7 (71)1.0

Test sensitivity for colorectal cancer (Table 1)

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Patient population
  6. Hemoccult SENSA
  7. FlexSure OBT
  8. Correlation with clinical findings
  9. Statistical analysis
  10. Results
  11. Test sensitivity for colorectal cancer ()
  12. Test sensitivity for significant colorectal neoplasia ()
  13. Combined approach (Hemoccult SENSA plus FlexSure OBT)
  14. Discussion
  15. Acknowledgements
  16. References

Nine cases of colorectal cancer were diagnosed by colonoscopy. There was one case of Dukes' A, four cases of Dukes' B, one case of Dukes' C and three cases of Dukes' D cancers. All colorectal cancers were detected by Hemoccult SENSA. However, FlexSure OBT was negative in one patient with rectal Dukes' A cancer. The sensitivity, specificity and positive predictive value of Hemoccult SENSA for the detection of colorectal cancer were 100%, 70% and 16%, respectively, whereas the same values for FlexSure OBT were 89%, 94% and 42%, respectively. As the number of cancers was only nine and the difference was small, statistical comparison was not warranted for sensitivity. However, FlexSure OBT showed a significantly higher specificity for cancer than did Hemoccult SENSA (P < 0.001; odds ratio = 6.7; 95% confidence interval, 2.7–17.1).

Test sensitivity for significant colorectal neoplasia (Table 1)

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Patient population
  6. Hemoccult SENSA
  7. FlexSure OBT
  8. Correlation with clinical findings
  9. Statistical analysis
  10. Results
  11. Test sensitivity for colorectal cancer ()
  12. Test sensitivity for significant colorectal neoplasia ()
  13. Combined approach (Hemoccult SENSA plus FlexSure OBT)
  14. Discussion
  15. Acknowledgements
  16. References

For significant colorectal neoplasia (adenomas ≥ 1.0 cm in diameter or cancer), the detection rate of Hemoccult SENSA (91%) was similar to that of FlexSure OBT (82%), but the specificity of FlexSure OBT was higher than that of Hemoccult SENSA. There was no difference between Hemoccult SENSA and FlexSure OBT in the detection rate for significant colorectal neoplasia above and below the splenic flexure. Two patients had an adenoma greater than 1.0 cm. Both Hemoccult SENSA and FlexSure OBT failed to detect one rectal adenoma of 2.0 cm in diameter. The positive predictive value of FlexSure OBT was significantly higher than that of Hemoccult SENSA for significant neoplasia (47% vs. 18%, P = 0.016).

Combined approach (Hemoccult SENSA plus FlexSure OBT)

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Patient population
  6. Hemoccult SENSA
  7. FlexSure OBT
  8. Correlation with clinical findings
  9. Statistical analysis
  10. Results
  11. Test sensitivity for colorectal cancer ()
  12. Test sensitivity for significant colorectal neoplasia ()
  13. Combined approach (Hemoccult SENSA plus FlexSure OBT)
  14. Discussion
  15. Acknowledgements
  16. References

Using the approach described by Allison et al.17 (both tests must be positive for a positive result), the sensitivity, specificity and positive predictive value for the detection of colorectal cancer (89%, 94% and 42%) and significant colorectal neoplasia (82%, 94% and 47%) were no better than those of FlexSure OBT alone.

Discussion

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Patient population
  6. Hemoccult SENSA
  7. FlexSure OBT
  8. Correlation with clinical findings
  9. Statistical analysis
  10. Results
  11. Test sensitivity for colorectal cancer ()
  12. Test sensitivity for significant colorectal neoplasia ()
  13. Combined approach (Hemoccult SENSA plus FlexSure OBT)
  14. Discussion
  15. Acknowledgements
  16. References

This is the first report of an endoscopically controlled comparative faecal occult blood test study in a Chinese population. Although the total number of study subjects was small and all patients were recruited after the decision to perform colonoscopy had been made, we were able to obtain useful information on the relative specificity of the two types of faecal occult blood test. However, only limited information could be obtained on the sensitivity of the two types of faecal occult blood test for clinically significant neoplasia.

The high positivity rate with Hemoccult SENSA and the consequent relatively poor specificity raise significant concerns about its suitability for screening the asymptomatic Hong Kong population. Although the study population was not a true screening population and the incidence of symptoms was higher than would be expected in that setting, 99 patients had normal colonoscopy findings and 30 of these were positive by Hemoccult SENSA. Such a high positivity rate would lead to an unnecessarily high colonoscopy rate, with considerable implications with regard to procedural risks and costs to the Chinese population at risk for colorectal cancer.

Extensive colorectal cancer screening experience has been obtained in Japan, and it has been concluded that a 2-day immunochemical test for faecal occult blood is more suitable than the guaiac test for the Japanese population due to the high positivity rate of the guaiac test in that population.18 Unfortunately, FlexSure OBT is no longer available in the USA, but was used as a prototype of an office-developed immunochemical faecal occult blood test in our study.

In our study design, dietary restriction was not requested of the participants. We believed that dietary restriction would have been difficult to control as it would not have been widely accepted in our Chinese population. It has been suggested that, when using the guaiac-based faecal occult blood test, the omission of dietary restriction does not have a major effect on positivity rates in populations eating a Western diet.14 Furthermore, delayed development of the guaiac-based faecal occult blood test for 3 days may minimize plant peroxidase activity.13, 15 Taking into consideration the available data on dietary restriction and delayed development of the guaiac-based faecal occult blood test, and in order to optimize compliance, we decided to perform the study without dietary restriction. In general, the Chinese population consumes relatively little red meat but a high fruit and vegetable diet every day. With no dietary restrictions,14 and despite delaying the development of Hemoccult SENSA for at least 3 days in order to allow for the breakdown of unstable vegetable peroxidases,13, 15, 16 Hemoccult SENSA still showed a high false-positive rate. The reason for this is not clear and could be due to a very high plant peroxidase component of the diet or the consumption of red meat. Our results with the Hemoccult SENSA test suggest that delaying slide processing does not effectively eliminate most dietary-induced false positivity in our population. These results are not in accord with the Food and Drug Administration-approved product instructions for Hemoccult SENSA, which state that no limitation is required for peroxidase-containing foods during the faecal occult blood test and that Hemoccult SENSA slides are ‘best developed no sooner than 3 days after sample application’. Our data may also apply to other multi-ethnic populations, in whom dietary compliance is sometimes difficult to control, and could lead to unnecessary high positivity rates of sensitive guaiac-based faecal occult blood tests. In several screening studies performed in Western populations, the overall positivity rate of Hemoccult SENSA ranged from 5% to 16.7%, but delayed processing of Hemoccult SENSA was not uniformly practised in these studies.12, 15 Although the positivity rates in these studies were not as high as the 41% observed in our study, they would still lead to a relatively high colonoscopy rate, and a significant demand on the health resources required.

This study has two limitations. Firstly, a highly selected population undergoing colonoscopy for several ‘high-risk’ indications was investigated, and so care should be taken when applying our results to an average-risk, asymptomatic population. Nevertheless, we feel that useful information was obtained about the feasibility and relative specificity of the two faecal occult blood tests in our Chinese population. Secondly, in our population, the elimination of dietary restriction seemed to lead to a distinct disadvantage for the Hemoccult SENSA test, even when delaying its development to reduce the activity of dietary peroxidases. Unfortunately, our results suggested that this approach may not be as effective as shown in populations consuming a Western diet. It would appear that, in our population, we need to restrict the diet in order to control the specificity of the guaiac-based faecal occult blood test. We do not believe that this is feasible.

In conclusion, we have shown that FlexSure OBT, an immunochemical faecal occult blood test, is more specific and appears to be more accurate than the guaiac-based Hemoccult SENSA test for the detection of significant colorectal neoplasia in a Chinese population. Although this constitutes a pilot study only, it provides some guidance as to which type of faecal occult blood test may be appropriate for large-scale screening programmes in Chinese populations. Future larger scale screening studies are warranted to evaluate the most appropriate faecal occult blood test.

Acknowledgements

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Patient population
  6. Hemoccult SENSA
  7. FlexSure OBT
  8. Correlation with clinical findings
  9. Statistical analysis
  10. Results
  11. Test sensitivity for colorectal cancer ()
  12. Test sensitivity for significant colorectal neoplasia ()
  13. Combined approach (Hemoccult SENSA plus FlexSure OBT)
  14. Discussion
  15. Acknowledgements
  16. References

The Gastroenterological Research Fund and the Simon K. Y. Lee Gastroenterology Research Fund, University of Hong Kong, Queen Mary Hospital, Hong Kong, supported this study. We are grateful to Ronald J. Schoengold (former employee and current consultant to Beckman Coulter, Inc.) and members of the World Organization for Digestive Endoscopy (OMED)/WHO/American Society for Gastrointestinal Endoscopy, ‘Outreach’ Program for the International Promotion of Colorectal Cancer Screening, for their advice on the development of the study protocol and its evaluation. We would also like to thank Beckman Coulter, Inc., USA, for providing the Hemoccult II/SENSA and FlexSure OBT test kits. We thank Ms. Fiona M. Y. Fung and endoscopy nurses of the Departments of Medicine and Surgery, Queen Mary Hospital, for their assistance and provision of care to the patients.

References

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Patient population
  6. Hemoccult SENSA
  7. FlexSure OBT
  8. Correlation with clinical findings
  9. Statistical analysis
  10. Results
  11. Test sensitivity for colorectal cancer ()
  12. Test sensitivity for significant colorectal neoplasia ()
  13. Combined approach (Hemoccult SENSA plus FlexSure OBT)
  14. Discussion
  15. Acknowledgements
  16. References
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    Sinatra MA, St John DJ, Young GP. Interference of plant peroxidases with guaiac-based fecal occult blood tests is avoidable. Clin Chem 1999; 45: 1236.
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    Pignone M, Campbell MK, Carr C, Phillips C. Meta-analysis of dietary restriction during fecal occult blood testing. Eff Clin Pract 2001; 4: 1506.
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    Rozen P, Knaani J, Samuel Z. Comparative screening with a sensitive guaiac and specific immunochemical occult blood test in an endoscopic study. Cancer 2000; 89: 4652.
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    Allison JE, Tekawa IS, Ransom LJ, Adrain AL. A comparison of fecal occult-blood tests for colorectal-cancer screening. N Engl J Med 1996; 334: 1559.
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    Saito H, Yoshida Y. Mass screening: Japanese perspective. In: YoungGP, RozenP, LevinB, eds. Prevention and Early Detection of Colorectal Cancer. London: Saunders, 1996: 30112.