World Congress at ACG2017

Presidential Plenary Session 1 (Free Paper/Abstract Presentations)

1 - Risk of Metachronous High-Risk Adenomas and Large (>/= 1 cm) Serrated Polyps in Individuals With Serrated Polyps on Index Colonoscopy: Longitudinal Data From the New Hampshire Colonoscopy Registry

Monday, October 16
8:00 AM - 8:12 AM
Location: Valencia Ballroom (Level 4)



Award: 2017 Category Award (Colon)

Category: Colon       

Joseph C. Anderson, MD, MHCDS1, Amitabh Srivastava, MD2, Christina Robinson, MS3, Julie Weiss, MS1, Christopher Amos, PhD1, Lynn Butterly, MD3
1Dartmouth College Geisel School of Medicine, Hanover, NH; 2Brigham & Women's Hospital, Boston, MA; 3Dartmouth-Hitchcock Medical Center, Lebanon, NH
Introduction: There are limited longitudinal data for the risk of metachronous high risk adenomas (HRA) in adults with clinically significant SPs on index colonoscopy. Clinically significant SPs may include large (>/= 1 cm) SPs, sessile serrated polyps (SSP) or traditional serrated adenomas (TSA). One important clinical question is whether the presence of SPs in adults with LRA increase the risk for metachronous HRA versus having LRA only. Existing data are limited by sample size. We used the population based New Hampshire Colonoscopy Registry (NHCR) to examine the risk of metachronous large (>/= 1 cm) SPs and HRA associated with serrated polyps (SPs) on index colonoscopy as characterized by SP size or histology.

Methods: We used 2 separate schemes to stratify adults by index SPs: 1) SIZE (SPs >/= 1cm vs < 1cm) AND 2) HISTOLOGY (SSP or TSA vs hyperplastic polyps (HP)). We further stratified SP groups by presence or absence of synchronous HRA (adenoma >/= 1cm, villous, high grade dysplasia, multiple (> 2), cancer). Reference group had normal exams. We used logistic regression to adjust for risk factors (age, sex, BMI, smoking, follow up time) and calculate 2 metachronous risks: 1) HRA; 2) Large SPs >/=1cm).

Results: We excluded adults with index HRA leaving 4,616 adults (median age 61 yrs; 49.7% men) with 2 colonoscopies (median time to surveillance: 4.9 yrs)(6/2004-6/2015). Overall, the risk for metachronous HRA was 6.3% and large SP was 1.2%. We adjusted for patient age, sex, smoking, BMI and time between the 2 exams. Index LRA were associated with an increased metachronous HRA risk (see Table). There was no increased risk for adults with LRA and SPs for metachronous HRA as compared to LRA alone. Index SPs alone regardless of size or histology were not associated with an increased risk for HRA in adults with no index LRA. However, large SPs (>14 fold) and SSP/TSAs (> 10 fold) were strongly associated with metachronous large SPs.

Discussion: While having index LRA was associated with an increased HRA risk on surveillance exam, significant index SPs (large (>/= 1 cm) or SSP/TSA) alone without LRA were not associated with an increased HRA risk. There was no added HRA risk for adults with synchronous LRA and SPs. However significant SPs with or without LRA were strongly correlated with increased risk for large SPs which are associated with CRC in longitudinal studies (Holme GUT 2015). These data support continued surveillance of adults with clinically significant SPs.

Supported by Industry Grant: No


*Adjusted OR (95% C)I for metachronous findings by index colonoscopy findings characterized by low risk adenoma and serrated polyp size and histology on index exam for 4,616 NHCR participants with 2 colonoscopies (1/2004 – 6/2015)





















































































Index Findings  N Metachronous
HRA risk
*Adjusted OR (95% CI)
Metachronous
large serrated polyp (>/= 1 cm) Risk
*Adjusted OR (95% CI)
No LRA No SP 2396  1.0 (Reference)  1.0 (Reference)
Serrated polyps on index
No LRA SP < 1cm 452 0.73 (0.42-1.28) 1.20 (0.40-3.62)
No LRA SP >/= 1 cm 65 0.83 (0.20-3.49) 14.57 (5.19-40.88)
No LRA SSP/TSA 104 0.83 (0.26-2.70) 10.29 (3.91-27.13)
No LRA HP 698 0.72 (0.43-1.19)  1.96 (0.83-4.61)
LRA on index
LRA SP < 1 cm
272 2.09 (1.32-3.31) 2.59 (0.93-7.17)
LRA SP >/= 1 cm 22 1.83 (0.41-8.11) 22.28 (5.50-90.34)
LRA SSP/TSA 49 2.88 (1.67-7.13) 9.33 (2.47-32.28)
LRA HP 378 2.19 (1.45-3.31) 2.80 (1.13-6.97)
LRA No SP 991 1.93 (1.41-2.62) 0.31 (0.07-1.37)

*Adjusted for patient age, gender, smoking status, BMI and median time between the 2 colonoscopies

Citation: . RISK OF METACHRONOUS HIGH-RISK ADENOMAS AND LARGE (>/= 1 CM) SERRATED POLYPS IN INDIVIDUALS WITH SERRATED POLYPS ON INDEX COLONOSCOPY: LONGITUDINAL DATA FROM THE NEW HAMPSHIRE COLONOSCOPY REGISTRY. Program No. 1. World Congress of Gastroenterology at ACG2017 Meeting Abstracts. Orlando, FL: American College of Gastroenterology.

Joseph C. Anderson

Associate Professor of Medicine
Dartmouth College Geisel School of Medicine
Hanover, NH

Joseph C. Anderson is a practicing gastroenterologist at the White River Junction VAMC and an Associate Professor of Medicine at the Geisel School of Medicine at Dartmouth College. He has published on many aspects of CRC screening including risk factors, technical performance, screening the underinsured and CT Colonography. He co-authored the ACG 2009 CRC screening guidelines. He is also a co-investigator in the New Hampshire Colonoscopy Registry which is a statewide database designed to provide data to maximize the efficiency of screening colonoscopy.

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