B0174 - Risk Factors Impacting Advanced Adenoma Detection Rate Following Negative Multitarget Stool DNA Testing

Monday, October 24, 2022

10:00 AM – 12:00 PM ET

Location: Crown Ballroom

Has Audio

Presenting Author(s)

Ahmed M. Ibrahim, MD

Henry Ford Hospital
Bloomfield Hills, Michigan

Ahmed M. Ibrahim, MD¹, Suraj Suresh, MD², Muhammad Salman Faisal, MD², Kevin Harris, MD³, Raef A. Fadel, DO², Mostafa Ibrahim, MD, FACG²
¹Henry Ford Hospital, Bloomfield Hills, MI; ²Henry Ford Hospital, Detroit, MI; ³Henry Ford Health System, Detroit, MI

Introduction: Colonoscopy remains the gold standard for colorectal cancer (CRC) screening, but less invasive screening modalities have been employed more recently, including the multitarget Stool DNA (MT-sDNA or Cologuard) test, which combines detection of blood products with genetic markers in the stool. Data regarding the false-negative rate of the MT-sDNA test in real-world clinical practice is limited. Our primary aim was to determine the rate of false-negative MT-sDNA testing and evaluate for factors associated with higher false-negative rates within our health system.

Methods: Adults (≥18 years old) with a negative MT-sDNA test between 2017 and 2022 and subsequent colonoscopy within three years of the MT-sDNA test, regardless of colonoscopy indication were included. Our primary outcome of interest was advanced adenoma (AA) detection rate, defined as adenoma with villous features, size ≥ 1.0 cm, high-grade dysplasia, or early invasive cancer. Demographic and procedural variables including age, sex, race, BMI, colonoscopy indication, polyp size, and polyp location were manually extracted from patient charts and compared between the two groups (AA vs. no AA) using chi-squared analysis.

Results: A total of 370 patients met the inclusion criteria, of which 31 (8.4%) were found to have AA and 3 (0.81%) were found to have CRC on colonoscopy within 3 years of negative MT-sDNA test. There were no demographic differences between the two groups. AA detection rate was significantly higher in patients who underwent colonoscopy for GI bleeding (32.3% vs 14.2%, p=0.008) as opposed to other indications. Among patients who had polyps (N=148), AA detection was associated with more numerous polyps (2 [IQR 1-4] vs 1 [IQR 1-2], p < 0.001), and larger polyp size (14 [SD 5.1] vs 5.1 [SD 2.2], p < 0.001). AAs were also significantly more frequently found in the hepatic flexure (6.5% vs 0.3%, p=0.050) and transverse colon (41.9% vs 5.6%, p=0.002) compared to other locations.

Discussion: The results of this study validate the 8% quoted false-negative rate for MT-sDNA testing shown in prior literature. Large polyps in the transverse colon and hepatic flexure are more likely to result in a false negative MT-sDNA test and therefore these locations should be examined in more detail during endoscope withdrawal. Finally, a negative MT-sDNA test result should be interpreted with caution and gastroenterologists should have a low threshold to perform a colonoscopy if otherwise clinically indicated.

		Advanced Adenoma		Non-Advanced Adenoma		p value
		n=31		n=339

Male Sex, n(%)	n(%)	16	51.6%	126	37.2%	0.114
Age – years	median(IQR)	67	59-74	66	59-71	0.157
Race	n(%)					0.168
White		28	90.3%	272	80.2%
Black		3	9.7%	59	17.4%
Other		0	0.0%	8	2.4%
BMI – kg/m²	median(IQR)	30.7	25.6-35.2	30.1	26-34	0.807
Personal History of Colon Cancer	n(%)	0	0.0%	3	0.9%	0.600
Family History of Colon Cancer	n(%)	0	0.0%	32	9.4%	0.074
Personal History of IBD	n(%)	0	0.0%	3	0.9%	0.600
Indication for Colonoscopy	n(%)
GI Bleeding		10	32.3%	48	14.2%	0.008
Iron deficiency anemia		4	12.9%	28	8.3%	0.380
Diarrhea		1	3.2%	34	10.0%	0.216
Constipation		0	0.0%	6	1.8%	0.457
Weight loss		0	0.0%	5	1.5%	0.497
Abnormal Imaging		2	6.5%	11	3.2%	0.355
IBD		0	0.0%	0	0.0%
Screening		14	45.2%	193	56.9%	0.207
Other		0	0.0%	14	4.1%	0.250
Prep Quality	n(%)
Poor		2	6.5%	24	7.1%	0.896
Inadequate		0	0.0%	2	0.6%	0.669
Fair		10	32.3%	79	23.3%	0.265
Adequate		2	6.5%	35	10.3%	0.493
Good		17	54.8%	187	55.2%	0.972
Excellent		0	0.0%	12	3.5%	0.288

Table: Baseline demographics and procedural variables in patients with negative MT-sDNA testing and advanced adenoma on colonoscopy (n=31) as compared to patients without advanced adenoma (n=339).

Disclosures:

Ahmed Ibrahim indicated no relevant financial relationships.

Suraj Suresh indicated no relevant financial relationships.

Muhammad Salman Faisal indicated no relevant financial relationships.

Kevin Harris indicated no relevant financial relationships.

Raef Fadel indicated no relevant financial relationships.

Mostafa Ibrahim indicated no relevant financial relationships.

Ahmed M. Ibrahim, MD¹, Suraj Suresh, MD², Muhammad Salman Faisal, MD², Kevin Harris, MD³, Raef A. Fadel, DO², Mostafa Ibrahim, MD, FACG². B0174 - Risk Factors Impacting Advanced Adenoma Detection Rate Following Negative Multitarget Stool DNA Testing, ACG 2022 Annual Scientific Meeting Abstracts. Charlotte, NC: American College of Gastroenterology.