Small and Diminutive Polyps Detected at Screening CT Colonography: A Decision Analysis for Referral to Colonoscopy
Perry J. Pickhardt1,2,
Cesare Hassan3,
Andrea Laghi4,
Angelo Zullo3,
David H. Kim1,
Franco Iafrate5 and
Sergio Morini3
1 Department of Radiology, University of Wisconsin Medical School, E3/311
Clinical Science Center, 600 Highland Ave., Madison, WI 53792-3252.
2 Department of Radiology, Uniformed Services University of the Health Sciences,
Bethesda, MD.
3 Gastroenterology and Digestive Endoscopy Unit, "Nuovo Regina
Margherita" Hospital, Rome, Italy.
4 Department of Radiological Sciences, "Sapienza" - University or
Rome, Polo Pontino, I.C.O.T. Hospital, Latina, Italy.
5 Department of Radiological Sciences, University of Rome La Sapienza
"Policlinico Umberto I," Rome, Italy.
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Fig. 1 —Decision tree that models decision of whether to remove polyp
detected in 60-year-old asymptomatic adult undergoing CT colonography (CTC)
screening. Two strategies for CTC-detected polyps, colonoscopic polypectomy
versus no colonoscopy, are modeled over 10-year period. No-colonoscopy
strategy is equivalent to nonreporting of polyps at CTC. This decision tree
applies to all three polyp size categories. Triangle at end of course
signifies that patient will remain in that state until end of study period.
CRC = colorectal cancer.
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Fig. 2 —Schematic representation of simulated population without CT
colonography screening intervention. Expected number of advanced adenomas and
colorectal cancer (CRC) cases were derived using assumptions described in
text. Note that 24% of CRC is considered to be unpreventable by polyp
screening based on findings from National Polyp Study
[20]. Given relative paucity
of firm natural history data for colorectal polyps, 10-year CRC risk for
subcentimeter advanced lesions was conservatively assumed to be the same as
that for large advanced lesions, which likely overestimates importance of
small polyps.
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Fig. 3A —Sensitivity analysis and Monte Carlo simulation for diminutive
polyps ( 5 mm). Graph shows incremental cost-effectiveness ratio (ICER)
and number of CT colonography (CTC)-detected polyps needed to be removed to
prevent one colorectal cancer over 10 years (NPR-CRC), according to prevalence
of diminutive advanced neoplasms.
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Fig. 3B —Sensitivity analysis and Monte Carlo simulation for diminutive
polyps ( 5 mm). Graphs show ICER relative to variations in CTC sensitivity
(B) and specificity (C). Baseline refers to case base
assumption.
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Fig. 3C —Sensitivity analysis and Monte Carlo simulation for diminutive
polyps ( 5 mm). Graphs show ICER relative to variations in CTC sensitivity
(B) and specificity (C). Baseline refers to case base
assumption.
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Fig. 3D —Sensitivity analysis and Monte Carlo simulation for diminutive
polyps ( 5 mm). Graph shows distribution of frequencies of ICER when
simulating 10,000 simultaneous variations of baseline values at Monte Carlo
analysis. Vertical lines refer to 10th and 90th percentiles. See text for
additional discussion.
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Fig. 4A —Sensitivity analysis and Monte Carlo simulation for small polyps
(6-9 mm). Graph shows incremental cost-effectiveness ratio (ICER) and number
of CT colonography (CTC)-detected polyps needed to be removed to prevent one
colorectal cancer (CRC) over 10 years (NPR-CRC), according to prevalence of
small advanced neoplasms.
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Fig. 4B —Sensitivity analysis and Monte Carlo simulation for small polyps
(6-9 mm). Graphs show ICER relative to variations in sensitivity (B)
and specificity (C). Baseline refers to case base assumption.
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Fig. 4C —Sensitivity analysis and Monte Carlo simulation for small polyps
(6-9 mm). Graphs show ICER relative to variations in sensitivity (B)
and specificity (C). Baseline refers to case base assumption.
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Fig. 4D —Sensitivity analysis and Monte Carlo simulation for small polyps
(6-9 mm). Graph shows distribution of frequencies of ICER when simulating
10,000 simultaneous variations of baseline values at Monte Carlo analysis.
Vertical lines refer to 10th and 90th percentiles. See text for additional
discussion.
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Copyright © 2008 by the American Roentgen Ray Society.
