Smoking and Other Risk Factors in Individuals With Synchronous Conventional High-Risk Adenomas and Clinically Significant Serrated Polyps.

BACKGROUND AND AIMS: Serrated polyps (SPs) and conventional high-risk adenomas (HRAs) derive from two distinct biological pathways but can also occur synchronously. Adults with synchronous SPs and adenomas have been shown to be a high-risk group and may have a unique risk factor profile that differs from adults with conventional HRAs alone. We used the population-based New Hampshire Colonoscopy Registry (NHCR) to examine the risk profile of individuals with synchronous conventional HRAs and SPs. METHODS: Our study population included 20,281 first time screening colonoscopies from asymptomatic NHCR participants 40 years or older between 2004-15. Exams were categorized by findings: (1) normal, (2) HRA only (adenomas ≥ 1 cm, villous, high grade dysplasia, multiple adenomas ( > 2) and adenocarcinoma), (3) clinically significant SP (CSSP) only (any hyperplastic polyp ≥ 1 cm, sessile serrated adenomas/polyps or traditional serrated adenomas), and (4) synchronous HRA + CSSP. Risk factors examined included exposure of interest, smoking (never, past, and current/pack years), as well as age, sex, alcohol, education, and family history of colorectal cancer (CRC). Multivariable unconditional logistic regression tested the relation of risk factors with having synchronous HRA + CSSP versus having a normal exam or HRA alone. RESULTS: Among NHCR participants with 18,354 screening colonoscopies (with complete smoking, sex, bowel preparation data, and adequate preparation) there were 16,495 normal; 1309 HRA alone; 461 CSSP alone, and 89 synchronous HRA + CSSP. Current smoking was associated with an almost threefold increased risk for HRA or CSSP, and an eightfold risk for synchronous HRA + CSSP (aOR = 8.66; 95% CI: 4.73-15.86) compared to normal exams. Adults with synchronous HRA + CSSP were threefold more likely to be current smokers than those with HRA alone (aOR = 3.27; 95% CI:1.74-6.16). CONCLUSIONS: Our data suggest that current smokers may be at a higher risk for synchronous CSSP + HRA even when compared to having HRA alone.