Purpose: While serrated adenomas may represent a separate and important pathway for colorectal cancer (CRC), little is known about the risk factors for these lesions. Methylation abnormalities such as BRAF have been observed in serrated adenomas and smokers. Our hypothesis was that smoking may be associated with these lesions.
Methods: All patients diagnosed with serrated adenomas from January 2007 to May 2010 were identified retrospectively based on a pathology database query. Controls, who had no adenomas on colonoscopy, were randomly identified from a period of 2007-2010. Data collected included age, gender, ethnicity, height, weight, family history of CRC, diabetes, use of ASA, statins and calcium. We defined smoking as those patients who smoked at least 20 pack years.
Results: We identified 100 patients with serrated adenomas of any size and 200 controls with no adenomas. Of the 100 serrated adenomas, 47 were 6 mm or larger and 25 of them were >1 cm. Smoking, obesity (BMI >30), and age were significantly correlated with risk for serrated adenomas (see Table 1). Diabetes was also correlated with the risk of serrated adenomas but it was also very tightly associated with BMI and so it was omitted from the final equation. We examined the relationship between smoking and obesity further since they were both strongly associated with risk for serrated adenomas. Patients who had both risks, obesity AND smoking, were at significantly increased risk when compared to those who had only one risk, either smoked OR were obese but not both (Adjusted Odds Ratio=5.37; 95 % Confidence Interval: 2.24-12.85). Both groups had an increased risk over patients who did not smoke and were thin (see Table 2).
Conclusion: Our data suggest that smoking more than 20 pack years appears to be a risk for serrated adenomas. In addition, obesity is strongly associated with serrated adenomas, perhaps related to the increased risk for diabetes in obese patients. Together both risk factors increase the risk in a synergistic fashion.