The Long-term Impact of Roux-en-Y Gastric Bypass on Colorectal Polyp Formation and Relation to Weight Loss Outcomes
Evolving epidemiological data, backed by mechanistic evidence, supports a paradoxical increase in the risk of colorectal cancer after Roux-en-Y gastric bypass surgery (RYGB). We examined the risk of colonic polyps after RYGB.
A single-center retrospective study included colonoscopies performed between the years 1994 and 2018. To focus on the long-term impact of RYGB on precancerous colonic polyps, we compared patients at average risk for CRC who underwent colonoscopy ≥ 5 years after RYGB (n = 86) versus pre-RYGB (n = 106). We analyzed our data using inverse probability of treatment weighting (IPTW) using propensity scores in order to account for multiple potential confounders.
After IPTW, we found no statistical differences between pre- and post-RYGB patients for risk of any polyp (33.2% pre- vs. 32.7% post-RYGB). However, the percentage of serrated polyps was higher ≥ 5 years post-RYGB compared with pre-RYGB (8.7% vs. 2.1%, p = 0.04, relative risk = 4.22; 95% CI 0.97, 18.4). Body mass index ≥ 30 kg/m2 at time of colonoscopy was associated with a greater risk for any polyp after RYGB (OR 6.23; 95% CI 1.16, 33.41). There was also a trend towards increased risk of polyps in post-RYGB patients who were current smokers (OR = 4.97; 95% CI 0.82, 30) or with age > 55 years (OR = 2.49; 95% CI 0.88, 7.00).
Our data suggest that RYGB is associated with an increased risk of serrated polyps after 5 years from surgery. Prospective studies defining this risk and examining mechanisms will be instrumental for application of CRC preventative strategies in this population.
KeywordsColorectal Polyps Neoplasia Roux-en-Y Gastric bypass Bariatric surgery
Roux-en-Y gastric bypass
Ohio State University Wexner Medical Center
Boston Bowel Preparation Scale
Body mass index
Inverse probability of treatment weighting
Dr. Hussan was involved in the conception, design, and interpretation of data and the manuscript’s drafting and critical revision. Mr. Kyle Porter was involved in the study’s design, acquired and statistically analyzed the data, and provided a critical revision of the manuscript. The above authors had full access to all the data in the study and take responsibility for the data’s integrity and the data analysis’ accuracy. Drs. Noria, Drosdak, Patel, Focht, and Clinton as well as Melissa Le Roux were involved in the design, data interpretation, and critical revision of the manuscript. All gave final approval of the submitted manuscript and take responsibility for the integrity of the work.
This work was supported by the Clinical and Translational Science Awards (CTSA) Program National Institute of Health Grant (UL1TR002733).
Compliance with Ethical Standards
Conflict of Interest
The authors declare that they have no conflicts of interest.
Statement of Informed Consent/Statement of Human and Animal Rights
We have the institutional IRB approval for this retrospective study as documented in our methods. The Ohio State University IRB approved the waiver of informed consent since this is a retrospective chart review that involves no interaction with study participants; and the study accessed information which would normally be accessed during clinical care for these patients.
Thus, the risk for potential harm from accessing this information or inadvertent disclosure of this information in the course of the research is minimal. Also, it would not be practicable to locate the patients and obtain consent. Many patients are no longer being seen at Ohio State or may be deceased. Finally, this was a de-identified study that contained no identifiable information. Thus, no identifying information is available in the article.
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