Clin Chem Lab Med 2014; aop
Letter to the Editor Callum G. Fraser* and Josep M. Auge on behalf of the PROCOLON Group
Faecal haemoglobin concentrations do vary across geography as well as with age and sex: ramifications for colorectal cancer screening DOI 10.1515/cclm-2014-1172 Received November 28, 2014; accepted November 30, 2014
Keywords: colorectal cancer; cut-off concentrations; faecal haemoglobin; faecal immunochemical test; screening. To the Editor, Faecal immunochemical tests (FIT) for haemoglobin (Hb) are now recognised as the best currently available non-invasive investigation for use in colorectal cancer (CRC) screening programmes [1]. Although FIT come in qualitative and quantitative analytical system formats, most programmatic screening uses quantitative FIT which provide numerical estimates of faecal haemoglobin (f-Hb) concentration. In spite of this notable advantage over qualitative FIT and the more traditional guaiac-based faecal occult blood tests (gFOBT) for which the manufacturer sets the cut-off concentration, most programmes apply a single cut-off f-Hb to decide who, and who not, to refer for further investigation, usually colonoscopy. There are numerous publications which demonstrate the effect of changing cut-off f-Hb on overall test characteristics [2]. As the cut-off f-Hb is lowered, the positivity rate and sensitivity for detection of significant colorectal neoplasia increase at the expense of positive predictive value and specificity (more false-positives). Moreover, it has been shown that f-Hb below any cut-off used in
*Corresponding author: Professor Callum G. Fraser, Centre for Research into Cancer Prevention and Screening, University of Dundee, Ninewells Hospital and Medical School, Dundee DD1 9SY, Scotland, UK, Phone: +44 1382553799, Fax: +44 1382383615, E-mail: [email protected] Josep M. Auge: Biochemistry and Molecular Genetics Department, Hospital Clinic, Colorectal Cancer Screening Program, Barcelona, Catalonia
screening is directly related to the risk of CRC and [3] to CRC mortality and all-cause death [4]. However, such studies have not investigated using different cut-off f-Hb selected by age and sex. This is in spite of the fact that it has been shown that f-Hb increases with age and is higher in men than women [5]. In addition, it has been shown that f-Hb in individuals with positive screening test results from FIT, when taken along with age and sex, can be used to stratify probability for the detection of advanced colorectal neoplasia [6]. However, although much is now know about f-Hb, it has been suggested that the data available on distributions by age and sex, unlike certain data, such as population-based reference intervals in laboratory medicine systems that have undergone harmonisation, are not transferrable over time and geography [7]: the distributions of f-Hb in three countries (Scotland, Taiwan and Italy) were not Gaussian and had kurtosis and positive skew. Most importantly, although f-Hb increased with age and was higher in men than in women in all three countries, the numerical values and the distributions were different in the three countries. It was concluded that such data on f-Hb are not transferable across geography for CRC screening. As a consequence, the f-Hb concentrations in the prevalence (first) screening round in the Barcelona Colorectal Cancer Screening Program were investigated to assess whether this hypothesis was correct. This comparison is rational since the analytical methodology was identical across the four countries: this is important since it may be that quantitative FIT analytical systems may not give identical results, probably due to the specificity of the antibodies employed in the immunoturbidimetric techniques used [8]. The distributions of f-Hb were generated from the results for 31,634 men and 39,141 women, aged between 50 and 69 years, so as to allow direct comparison with the data from the three other countries previously examined [7]. The organisation of the screening programme has been previously described
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2 Fraser and Auge: Variation of faecal haemoglobin concentrations
90 80 70 Faecal haemoglobin, μg/g
in detail [6]. Each participant collected one faecal sample using a specimen collection device (Eiken Chemical Co Ltd, Tokyo, Japan). Samples were analysed using an OCSensor Diana (Eiken), specimen devices were stored at 4 °C and then allowed to warm to room temperature for analysis. All analyses were performed by two clinical laboratory technicians; the laboratory has a total quality management system and is certified to ISO 9001:2008 standards by the Asociación Española de Normalización y Certificación (Spain). The analyser was calibrated once every 2 weeks with calibrators provided by the manufacturer (Eiken). Each analytical run was preceded by analysis of two quality control materials (Eiken), and analyses were performed every 200 samples. The combined weighted CV obtained was 4.0% at 25 μg Hb/g faeces (n = 594) and 4.1% at 90 μg Hb/g faeces (n = 594). Statistical analyses were performed using PASW Statistics 18 version 18.0.0 (SPSS, Inc, Chicago, IL, USA) and Graph- Pad Prism version 4.00 (GraphPad Software, San Diego, CA, USA). The data for four age groups, namely, 50 –54, 55– 59, 60 –64 and 65–69 years, were examined and the number of subjects in each age cohort, partitioned by sex, together with the 90.0, 85.0 and 97.5 percentiles are shown in Table 1. The results are given, as previously [7] in ng Hb/mL and μg Hb/g faces as recommended by an international expert group [9]. The 95.0 th percentile data for the four 5-year age groups are shown, by sex, in Figure 1. Comparison with the data from Scotland, Taiwan and Italy [7] shows that the f-Hb in men, in all four age cohorts in Barcelona, was higher than in any of the other three countries examined to date: further, the increase in f-Hb with age is greater in Barcelona. In contrast, women in Barcelona have very similar f-Hb distributions in each age cohort to those in Scotland, although higher than in Taiwan or Italy. There are a number of plausible reasons for this, as discussed previously [7],
60
Men Women
50 40 30 20 10
50–54
55–59 60–64 Age, years
65–69
Figure 1 Faecal haemoglobin (μg/g) for men and women in 4 age groups in Barcelona.
including lifestyle factors, such as diet and smoking habits and alcohol intake, number of previous screening episodes and pre-analytical factors. However, the most important conclusion is that it is confirmed that f-Hb do vary with age and sex, being higher in the more aged and men in all studies to date, but the degree of variation is inconsistent across countries. This supports the thesis that data on f-Hb are not transferrable across geography and any single f-Hb cut-off will give different outcomes in different countries. Moreover, since positivity rate is a surrogate marker for f-Hb, any factor that affects positivity, including age, sex, deprivation, ethnic group, number of previous screening exposures, analytical method and other factors, will be reflected in the f-Hb in the relevant group. In conclusion, this addendum to the existing literature on f-Hb supports the view that setting of one only fixed cut-off f-Hb in any CRC screening programmes is
Table 1 Percentiles of faecal haemoglobin concentration in ng haemoglobin/mL buffer (μg haemoglobin/g faeces) for four 5-year age groups in men and women in Barcelona. Sex
Age range, years
n, %
90.0%
95.0%
97.5%
Men Men Men Men Women Women Women Women
50–54 55–59 60–64 65–69 50–54 55–59 60–64 65–69
9465 (29.9) 7834 (24.8) 8024 (25.4) 6311 (20.0) 11520 (29.4) 9922 (25.3) 10076 (25.7) 7623 (19.5)
36 (7.2) 57 (11.4) 96 (19.2) 111 (22.2) 17 (3.4) 24 (4.8) 36 (7.2) 46 (9.2)
136 (27.2) 240 (48.0) 347 (69.4) 405 (81.0) 58 (11.6) 95 (19.0) 140 (28.0) 142 (28.4)
465 (93.0) 786 (157.2) 979 (195.8) 1299 (259.8) 173 (34.6) 275 (55.0) 434 (86.8) 381 (76.2)
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Fraser and Auge: Variation of faecal haemoglobin concentrations 3
not the optimum approach. The view that individualisation of CRC screening is the optimum approach using the f-Hb in an individual, alone or, probably better with other important factors, such as age and sex, as demonstrated in Barcelona [6], to determine important individual matters, such as the priority for colonoscopy. In addition, it is interesting that a number of countries, including the Netherlands and the Republic of Ireland have started CRC screening programmes using only cut-off f-Hb for all and have then run into difficulties of higher positivity than expected, leading to overwhelming demands on scarce colonoscopy resources. Most screening programmes are preceded by pilots: all pilots should do an analysis of the local country-specific f-Hb distributions so as to be able to assess, with a high degree of certainty, what the positivity rates would be by age and sex and what the consequences would be changing the cut-off(s) f-Hb or the groups invited for screening. Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission. Financial support: None declared. Employment or leadership: None declared. Honorarium: None declared. Competing interests: The funding organisation(s) played no role in the study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit the report for publication. Ethical approval and informed consent: Neither ethical approval nor individual informed consent were required for this study.
References 1. Carroll MR, Seaman HE, Halloran SP. Tests and investigations for colorectal cancer screening. Clin Biochem 2014;47:921–39. 2. Allison JE, Fraser CG, Halloran SP, Young GP. Population screening for colorectal cancer means getting FIT: the past, present, and future of colorectal cancer screening using FIT. Gut Liver 2014;8:117–30. 3. Chen LS, Yen AM, Chiu SY, Liao CS, Chen HH. Baseline faecal occult blood concentration as a predictor of incident colorectal neoplasia: longitudinal follow-up of a Taiwanese populationbased colorectal cancer screening cohort. Lancet Oncol 2011;12:551–8. 4. Chen LS, Yen AM, Fraser CG, Chiu SY, Fann JC, Wang PE, et al. Impact of faecal haemoglobin concentration on colorectal cancer mortality and all-cause death. Br Med J Open 2013;3:e003740. 5. McDonald PJ, Strachan JA, Digby J, Steele RJ, Fraser CG. Faecal haemoglobin concentrations by gender and age: implications for population-based screening for colorectal cancer. Clin Chem Lab Med 2012;50:935–40. 6. Auge JM, Pellise M, Escudero JM, Hernandez C, Andreu M, Grau J, et al. Risk stratification for advanced colorectal neoplasia according to fecal hemoglobin concentration in a colorectal cancer screening program. Gastroenterology 2014;14:628–36. 7. Fraser CG, Rubeca T, Rapi S, Chen LS, Chen HH. Faecal haemoglobin concentrations vary with sex and age, but data are not transferable across geography for colorectal cancer screening. Clin Chem Lab Med 2014;52:1211–6. 8. Chiang TH, Chuang SL, Chen SL, Chiu HM, Yen AM, Chiu SY et al. Difference in performance of fecal immunochemical tests with the same hemoglobin cutoff concentration in a nationwide colorectal cancer screening program. Gastroenterology 2014;147:1317–26. 9. Fraser CG, Allison JE, Halloran SP, Young GP; Expert Working Group on Fecal Immunochemical Tests for Hemoglobin, Colorectal Cancer Screening Committee, World Endoscopy Organization. A proposal to standardize reporting units for fecal immunochemical tests for hemoglobin. J Natl Cancer Inst 2012;104:810–4.
Brought to you by | Purdue University Libraries Authenticated Download Date | 5/27/15 4:56 AM
Letter to the Editor Callum G. Fraser* and Josep M. Auge on behalf of the PROCOLON Group
Faecal haemoglobin concentrations do vary across geography as well as with age and sex: ramifications for colorectal cancer screening DOI 10.1515/cclm-2014-1172 Received November 28, 2014; accepted November 30, 2014
Keywords: colorectal cancer; cut-off concentrations; faecal haemoglobin; faecal immunochemical test; screening. To the Editor, Faecal immunochemical tests (FIT) for haemoglobin (Hb) are now recognised as the best currently available non-invasive investigation for use in colorectal cancer (CRC) screening programmes [1]. Although FIT come in qualitative and quantitative analytical system formats, most programmatic screening uses quantitative FIT which provide numerical estimates of faecal haemoglobin (f-Hb) concentration. In spite of this notable advantage over qualitative FIT and the more traditional guaiac-based faecal occult blood tests (gFOBT) for which the manufacturer sets the cut-off concentration, most programmes apply a single cut-off f-Hb to decide who, and who not, to refer for further investigation, usually colonoscopy. There are numerous publications which demonstrate the effect of changing cut-off f-Hb on overall test characteristics [2]. As the cut-off f-Hb is lowered, the positivity rate and sensitivity for detection of significant colorectal neoplasia increase at the expense of positive predictive value and specificity (more false-positives). Moreover, it has been shown that f-Hb below any cut-off used in
*Corresponding author: Professor Callum G. Fraser, Centre for Research into Cancer Prevention and Screening, University of Dundee, Ninewells Hospital and Medical School, Dundee DD1 9SY, Scotland, UK, Phone: +44 1382553799, Fax: +44 1382383615, E-mail: [email protected] Josep M. Auge: Biochemistry and Molecular Genetics Department, Hospital Clinic, Colorectal Cancer Screening Program, Barcelona, Catalonia
screening is directly related to the risk of CRC and [3] to CRC mortality and all-cause death [4]. However, such studies have not investigated using different cut-off f-Hb selected by age and sex. This is in spite of the fact that it has been shown that f-Hb increases with age and is higher in men than women [5]. In addition, it has been shown that f-Hb in individuals with positive screening test results from FIT, when taken along with age and sex, can be used to stratify probability for the detection of advanced colorectal neoplasia [6]. However, although much is now know about f-Hb, it has been suggested that the data available on distributions by age and sex, unlike certain data, such as population-based reference intervals in laboratory medicine systems that have undergone harmonisation, are not transferrable over time and geography [7]: the distributions of f-Hb in three countries (Scotland, Taiwan and Italy) were not Gaussian and had kurtosis and positive skew. Most importantly, although f-Hb increased with age and was higher in men than in women in all three countries, the numerical values and the distributions were different in the three countries. It was concluded that such data on f-Hb are not transferable across geography for CRC screening. As a consequence, the f-Hb concentrations in the prevalence (first) screening round in the Barcelona Colorectal Cancer Screening Program were investigated to assess whether this hypothesis was correct. This comparison is rational since the analytical methodology was identical across the four countries: this is important since it may be that quantitative FIT analytical systems may not give identical results, probably due to the specificity of the antibodies employed in the immunoturbidimetric techniques used [8]. The distributions of f-Hb were generated from the results for 31,634 men and 39,141 women, aged between 50 and 69 years, so as to allow direct comparison with the data from the three other countries previously examined [7]. The organisation of the screening programme has been previously described
Brought to you by | Purdue University Libraries Authenticated Download Date | 5/27/15 4:56 AM
2 Fraser and Auge: Variation of faecal haemoglobin concentrations
90 80 70 Faecal haemoglobin, μg/g
in detail [6]. Each participant collected one faecal sample using a specimen collection device (Eiken Chemical Co Ltd, Tokyo, Japan). Samples were analysed using an OCSensor Diana (Eiken), specimen devices were stored at 4 °C and then allowed to warm to room temperature for analysis. All analyses were performed by two clinical laboratory technicians; the laboratory has a total quality management system and is certified to ISO 9001:2008 standards by the Asociación Española de Normalización y Certificación (Spain). The analyser was calibrated once every 2 weeks with calibrators provided by the manufacturer (Eiken). Each analytical run was preceded by analysis of two quality control materials (Eiken), and analyses were performed every 200 samples. The combined weighted CV obtained was 4.0% at 25 μg Hb/g faeces (n = 594) and 4.1% at 90 μg Hb/g faeces (n = 594). Statistical analyses were performed using PASW Statistics 18 version 18.0.0 (SPSS, Inc, Chicago, IL, USA) and Graph- Pad Prism version 4.00 (GraphPad Software, San Diego, CA, USA). The data for four age groups, namely, 50 –54, 55– 59, 60 –64 and 65–69 years, were examined and the number of subjects in each age cohort, partitioned by sex, together with the 90.0, 85.0 and 97.5 percentiles are shown in Table 1. The results are given, as previously [7] in ng Hb/mL and μg Hb/g faces as recommended by an international expert group [9]. The 95.0 th percentile data for the four 5-year age groups are shown, by sex, in Figure 1. Comparison with the data from Scotland, Taiwan and Italy [7] shows that the f-Hb in men, in all four age cohorts in Barcelona, was higher than in any of the other three countries examined to date: further, the increase in f-Hb with age is greater in Barcelona. In contrast, women in Barcelona have very similar f-Hb distributions in each age cohort to those in Scotland, although higher than in Taiwan or Italy. There are a number of plausible reasons for this, as discussed previously [7],
60
Men Women
50 40 30 20 10
50–54
55–59 60–64 Age, years
65–69
Figure 1 Faecal haemoglobin (μg/g) for men and women in 4 age groups in Barcelona.
including lifestyle factors, such as diet and smoking habits and alcohol intake, number of previous screening episodes and pre-analytical factors. However, the most important conclusion is that it is confirmed that f-Hb do vary with age and sex, being higher in the more aged and men in all studies to date, but the degree of variation is inconsistent across countries. This supports the thesis that data on f-Hb are not transferrable across geography and any single f-Hb cut-off will give different outcomes in different countries. Moreover, since positivity rate is a surrogate marker for f-Hb, any factor that affects positivity, including age, sex, deprivation, ethnic group, number of previous screening exposures, analytical method and other factors, will be reflected in the f-Hb in the relevant group. In conclusion, this addendum to the existing literature on f-Hb supports the view that setting of one only fixed cut-off f-Hb in any CRC screening programmes is
Table 1 Percentiles of faecal haemoglobin concentration in ng haemoglobin/mL buffer (μg haemoglobin/g faeces) for four 5-year age groups in men and women in Barcelona. Sex
Age range, years
n, %
90.0%
95.0%
97.5%
Men Men Men Men Women Women Women Women
50–54 55–59 60–64 65–69 50–54 55–59 60–64 65–69
9465 (29.9) 7834 (24.8) 8024 (25.4) 6311 (20.0) 11520 (29.4) 9922 (25.3) 10076 (25.7) 7623 (19.5)
36 (7.2) 57 (11.4) 96 (19.2) 111 (22.2) 17 (3.4) 24 (4.8) 36 (7.2) 46 (9.2)
136 (27.2) 240 (48.0) 347 (69.4) 405 (81.0) 58 (11.6) 95 (19.0) 140 (28.0) 142 (28.4)
465 (93.0) 786 (157.2) 979 (195.8) 1299 (259.8) 173 (34.6) 275 (55.0) 434 (86.8) 381 (76.2)
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Fraser and Auge: Variation of faecal haemoglobin concentrations 3
not the optimum approach. The view that individualisation of CRC screening is the optimum approach using the f-Hb in an individual, alone or, probably better with other important factors, such as age and sex, as demonstrated in Barcelona [6], to determine important individual matters, such as the priority for colonoscopy. In addition, it is interesting that a number of countries, including the Netherlands and the Republic of Ireland have started CRC screening programmes using only cut-off f-Hb for all and have then run into difficulties of higher positivity than expected, leading to overwhelming demands on scarce colonoscopy resources. Most screening programmes are preceded by pilots: all pilots should do an analysis of the local country-specific f-Hb distributions so as to be able to assess, with a high degree of certainty, what the positivity rates would be by age and sex and what the consequences would be changing the cut-off(s) f-Hb or the groups invited for screening. Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission. Financial support: None declared. Employment or leadership: None declared. Honorarium: None declared. Competing interests: The funding organisation(s) played no role in the study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit the report for publication. Ethical approval and informed consent: Neither ethical approval nor individual informed consent were required for this study.
References 1. Carroll MR, Seaman HE, Halloran SP. Tests and investigations for colorectal cancer screening. Clin Biochem 2014;47:921–39. 2. Allison JE, Fraser CG, Halloran SP, Young GP. Population screening for colorectal cancer means getting FIT: the past, present, and future of colorectal cancer screening using FIT. Gut Liver 2014;8:117–30. 3. Chen LS, Yen AM, Chiu SY, Liao CS, Chen HH. Baseline faecal occult blood concentration as a predictor of incident colorectal neoplasia: longitudinal follow-up of a Taiwanese populationbased colorectal cancer screening cohort. Lancet Oncol 2011;12:551–8. 4. Chen LS, Yen AM, Fraser CG, Chiu SY, Fann JC, Wang PE, et al. Impact of faecal haemoglobin concentration on colorectal cancer mortality and all-cause death. Br Med J Open 2013;3:e003740. 5. McDonald PJ, Strachan JA, Digby J, Steele RJ, Fraser CG. Faecal haemoglobin concentrations by gender and age: implications for population-based screening for colorectal cancer. Clin Chem Lab Med 2012;50:935–40. 6. Auge JM, Pellise M, Escudero JM, Hernandez C, Andreu M, Grau J, et al. Risk stratification for advanced colorectal neoplasia according to fecal hemoglobin concentration in a colorectal cancer screening program. Gastroenterology 2014;14:628–36. 7. Fraser CG, Rubeca T, Rapi S, Chen LS, Chen HH. Faecal haemoglobin concentrations vary with sex and age, but data are not transferable across geography for colorectal cancer screening. Clin Chem Lab Med 2014;52:1211–6. 8. Chiang TH, Chuang SL, Chen SL, Chiu HM, Yen AM, Chiu SY et al. Difference in performance of fecal immunochemical tests with the same hemoglobin cutoff concentration in a nationwide colorectal cancer screening program. Gastroenterology 2014;147:1317–26. 9. Fraser CG, Allison JE, Halloran SP, Young GP; Expert Working Group on Fecal Immunochemical Tests for Hemoglobin, Colorectal Cancer Screening Committee, World Endoscopy Organization. A proposal to standardize reporting units for fecal immunochemical tests for hemoglobin. J Natl Cancer Inst 2012;104:810–4.
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