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Sensitivity of immunochemical faecal occult blood testing for detecting left- vs right-sided colorectal neoplasia.

Haug U, Kuntz KM, Knudsen AB, Hundt S, Brenner H - Br. J. Cancer (2011)

Bottom Line: Faecal occult blood tests (FOBTs) are used for colorectal cancer (CRC) screening.In logistic regression analyses adjusted for site, pedunculated shape was statistically significantly associated with test sensitivity (P=0.04).Our findings may stimulate further diagnostic research in the field as well as modelling analyses to estimate the potential effect of site-specific test performance on the effectiveness of annual or biennial FOBT-based screening programmes, in particular with respect to protection from right-sided CRC.

View Article: PubMed Central - PubMed

Affiliation: Division of Clinical Epidemiology and Aging Research, German Cancer Research Center, Im Neuenheimer Feld 460, Heidelberg 69120, Germany. u.haug@dkfz.de

ABSTRACT

Background: Faecal occult blood tests (FOBTs) are used for colorectal cancer (CRC) screening. We aimed to assess the sensitivity of an immunochemical FOBT for detecting advanced colorectal neoplasia in the left vs the right colon and to explore reasons for potential differences in site-specific test performance.

Methods: We prospectively measured faecal occult blood levels by a quantitative immunochemical FOBT (RIDASCREEN) in 2310 average-risk subjects undergoing screening colonoscopy. We compared diagnostic performance for subjects with left- vs right-sided advanced neoplasia, as well as patient characteristics and adenoma characteristics that have been suggested to impact faecal haemoglobin levels.

Results: Sensitivities for subjects with left- vs right-sided advanced neoplasia were 33% (95% confidence interval (CI), 26-41%) and 20% (CI, 11-31%) (P=0.04) at a specificity of 95% (overall sensitivity: 29%) and the areas under the receiver-operating characteristics curve were 0.71 (CI, 0.69-0.72) and 0.60 (CI, 0.58-0.63), respectively. Pedunculated shape was strikingly more common in participants with left- vs right-sided advanced neoplasia (47% vs 14%). In logistic regression analyses adjusted for site, pedunculated shape was statistically significantly associated with test sensitivity (P=0.04).

Conclusions: The immunochemical FOBT in our study was more sensitive for detecting subjects with left- vs right-sided advanced colorectal neoplasia. Our findings may stimulate further diagnostic research in the field as well as modelling analyses to estimate the potential effect of site-specific test performance on the effectiveness of annual or biennial FOBT-based screening programmes, in particular with respect to protection from right-sided CRC.

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ROC curves for detecting patients with one advanced colorectal neoplasm (and no other colorectal adenomas) stratified by anatomical subsite, using a quantitative immunochemical FOBT. (In an ROC curve, the true positive rate (sensitivity) is plotted in function of the false positive rate (100−specificity) for different positivity thresholds (i.e., different cutoff levels) of a quantitative test (here, faecal haemoglobin levels). The AUC is a measure of how well a quantitative test can distinguish between subjects with and without a disease.)
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fig3: ROC curves for detecting patients with one advanced colorectal neoplasm (and no other colorectal adenomas) stratified by anatomical subsite, using a quantitative immunochemical FOBT. (In an ROC curve, the true positive rate (sensitivity) is plotted in function of the false positive rate (100−specificity) for different positivity thresholds (i.e., different cutoff levels) of a quantitative test (here, faecal haemoglobin levels). The AUC is a measure of how well a quantitative test can distinguish between subjects with and without a disease.)

Mentions: Sensitivity analyses focusing on subjects with only one advanced neoplasm (and no other adenomas) included 88 subjects with a left-sided neoplasm and 35 subjects with a right-sided neoplasm. The distribution of factors that may impact faecal haemoglobin levels in this restricted study population was similar to the distribution observed in the main analysis (Appendix). Figure 3 illustrates the ROC curves for detecting subjects with one advanced colorectal neoplasm (and no other adenomas), stratified by left- and right-sided location. While there was no clear difference at higher levels of specificity, the ROC curves for right- and left-sided advanced neoplasia diverged (towards higher sensitivities for left-sided advanced neoplasia) starting at a specificity of about 87%, which corresponds with a cutoff level of 2 μg haemoglobin per g stool. Again, the AUC was larger for the subgroup with one left-sided advanced neoplasm than for the subgroup with one right-sided advanced neoplasm and the difference persisted when further exclusion criteria were applied to decrease heterogeneity between subgroups with respect to the type and size of the advanced neoplasm (Table 2).


Sensitivity of immunochemical faecal occult blood testing for detecting left- vs right-sided colorectal neoplasia.

Haug U, Kuntz KM, Knudsen AB, Hundt S, Brenner H - Br. J. Cancer (2011)

ROC curves for detecting patients with one advanced colorectal neoplasm (and no other colorectal adenomas) stratified by anatomical subsite, using a quantitative immunochemical FOBT. (In an ROC curve, the true positive rate (sensitivity) is plotted in function of the false positive rate (100−specificity) for different positivity thresholds (i.e., different cutoff levels) of a quantitative test (here, faecal haemoglobin levels). The AUC is a measure of how well a quantitative test can distinguish between subjects with and without a disease.)
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3111170&req=5

fig3: ROC curves for detecting patients with one advanced colorectal neoplasm (and no other colorectal adenomas) stratified by anatomical subsite, using a quantitative immunochemical FOBT. (In an ROC curve, the true positive rate (sensitivity) is plotted in function of the false positive rate (100−specificity) for different positivity thresholds (i.e., different cutoff levels) of a quantitative test (here, faecal haemoglobin levels). The AUC is a measure of how well a quantitative test can distinguish between subjects with and without a disease.)
Mentions: Sensitivity analyses focusing on subjects with only one advanced neoplasm (and no other adenomas) included 88 subjects with a left-sided neoplasm and 35 subjects with a right-sided neoplasm. The distribution of factors that may impact faecal haemoglobin levels in this restricted study population was similar to the distribution observed in the main analysis (Appendix). Figure 3 illustrates the ROC curves for detecting subjects with one advanced colorectal neoplasm (and no other adenomas), stratified by left- and right-sided location. While there was no clear difference at higher levels of specificity, the ROC curves for right- and left-sided advanced neoplasia diverged (towards higher sensitivities for left-sided advanced neoplasia) starting at a specificity of about 87%, which corresponds with a cutoff level of 2 μg haemoglobin per g stool. Again, the AUC was larger for the subgroup with one left-sided advanced neoplasm than for the subgroup with one right-sided advanced neoplasm and the difference persisted when further exclusion criteria were applied to decrease heterogeneity between subgroups with respect to the type and size of the advanced neoplasm (Table 2).

Bottom Line: Faecal occult blood tests (FOBTs) are used for colorectal cancer (CRC) screening.In logistic regression analyses adjusted for site, pedunculated shape was statistically significantly associated with test sensitivity (P=0.04).Our findings may stimulate further diagnostic research in the field as well as modelling analyses to estimate the potential effect of site-specific test performance on the effectiveness of annual or biennial FOBT-based screening programmes, in particular with respect to protection from right-sided CRC.

View Article: PubMed Central - PubMed

Affiliation: Division of Clinical Epidemiology and Aging Research, German Cancer Research Center, Im Neuenheimer Feld 460, Heidelberg 69120, Germany. u.haug@dkfz.de

ABSTRACT

Background: Faecal occult blood tests (FOBTs) are used for colorectal cancer (CRC) screening. We aimed to assess the sensitivity of an immunochemical FOBT for detecting advanced colorectal neoplasia in the left vs the right colon and to explore reasons for potential differences in site-specific test performance.

Methods: We prospectively measured faecal occult blood levels by a quantitative immunochemical FOBT (RIDASCREEN) in 2310 average-risk subjects undergoing screening colonoscopy. We compared diagnostic performance for subjects with left- vs right-sided advanced neoplasia, as well as patient characteristics and adenoma characteristics that have been suggested to impact faecal haemoglobin levels.

Results: Sensitivities for subjects with left- vs right-sided advanced neoplasia were 33% (95% confidence interval (CI), 26-41%) and 20% (CI, 11-31%) (P=0.04) at a specificity of 95% (overall sensitivity: 29%) and the areas under the receiver-operating characteristics curve were 0.71 (CI, 0.69-0.72) and 0.60 (CI, 0.58-0.63), respectively. Pedunculated shape was strikingly more common in participants with left- vs right-sided advanced neoplasia (47% vs 14%). In logistic regression analyses adjusted for site, pedunculated shape was statistically significantly associated with test sensitivity (P=0.04).

Conclusions: The immunochemical FOBT in our study was more sensitive for detecting subjects with left- vs right-sided advanced colorectal neoplasia. Our findings may stimulate further diagnostic research in the field as well as modelling analyses to estimate the potential effect of site-specific test performance on the effectiveness of annual or biennial FOBT-based screening programmes, in particular with respect to protection from right-sided CRC.

Show MeSH
Related in: MedlinePlus