Effect of Cotinine-Verified Change in Smoking Status on Risk of Metachronous Colorectal Neoplasia After Polypectomy

BACKGROUND & AIMS

Previous assessments of colorectal neoplasia (CRN) recurrence after polypectomy used self-report to determine smoking status. We evaluated the association between change in smoking status and metachronous CRN risk after polypectomy using cotinine level in urine to determine tobacco exposure.

METHODS

We performed a retrospective study of participants in the Kangbuk Samsung Health Study in Korea who underwent a screening colonoscopy examination and measurement of cotinine in urine samples. Our analysis included 4762 patients who had 1 or more adenomas detected in an index colonoscopy performed between January 2010 and December 2014, and underwent a surveillance colonoscopy, 6 or more months later, until December 2017.

RESULTS

Patients were classified into 4 groups based on the change in cotinine-verified smoking status from index to follow-up colonoscopy (mean interval, 3.2 ± 1.3 y), as follows: remained nonsmokers (n = 2962; group 1), smokers changed to nonsmokers (n = 600; group 2), nonsmokers changed to smokers (n = 138; group 3), and remained smokers (n = 1062; group 4). After adjustment for confounding factors, group 4 had a significantly higher risk of metachronous CRN than group 1 (hazard ratio [HR], 1.54; 95% CI, 1.36-1.73) and group 2 (HR, 1.63; 95% CI, 1.39-1.99). Group 4 also had a higher risk of metachronous advanced CRN than group 1 (HR, 2.84; 95% CI, 1.79-4.53) and group 2 (HR, 2.10; 95% CI, 1.13-3.89). Group 3 had a higher risk of metachronous CRN than group 1 (HR, 1.50; 95% CI, 1.14-1.97) and group 2 (HR, 1.62; 95% CI, 1.20-2.20).

CONCLUSIONS

In a retrospective study of individuals with at least 1 adenoma, we found that cotinine-verified changes in smoking status between index and follow-up colonoscopy are associated with a risk of metachronous CRN. Helping patients quit smoking is important for effective prevention of colorectal cancer.