Smoking Is Associated With an Increased Risk of Adenomas in Patients at High Risk for Colorectal Cancer

Abstract

Introduction: Colorectal cancer (CRC) is the third leading cause of cancer mortality in the United States. Adenoma removal has been shown to reduce deaths from CRC. Although smoking has been associated with an increased risk of CRC, smoking status is not included in algorithms that guide colonoscopy for CRC screening and surveillance. This study evaluated the impact of smoking on adenoma detection in patients who are at elevated risk for CRC. Methods: Reports of consecutive colonoscopies performed at an urban university hospital during a 6-month period were reviewed and their indications and results noted. Colonoscopies performed for screening of elevated risk patients and/or surveillance indications were included. Elevated risk was defined as personal or family history of CRC or polyp, inflammatory bowel disease (IBD), or “high risk for CRC” as the stated indication. Patients’ demographics, family history, and smoking history were collected. Maintaining patient confidentiality, a database was created using Microsoft Excel. Statistical analysis was performed using Fisher’s exact test with significance set at p<0.05. The study was approved by the university IRB. Results: There were 589 screening or surveillance colonoscopies for elevated-risk patients. Among them, 373 never smoked and 216 had. Adenoma were detected in 123 elevated-risk patients who had smoked (56.9%) and 166 (44.5%) of the never smokers (p=0.0037). Family history was the sole risk factor for 79 patients deemed high risk (20 male, 59 female), and adenomas were discovered in 25 (31.6%). Colonoscopies were performed in 421 patients with history of polyp; 243 (57.7%) had adenomas. There were 56 IBD patients and 3 (5.4%) had adenomas. Among elevated CRC risk patients, smoking was associated with a higher adenoma detection rate than was IBD (p<0.001), and family history of CRC (p=0.001), but not personal history of colon polyp (p=0.8659). Conclusion: Adenoma detection and removal decreases CRC deaths. Personal and family history of CRC or adenoma and IBD are recognized risk factors and influence the recommended age of onset and interval of screening colonoscopy. In this study, there was a significantly higher adenoma detection rate in smokers at increased risk of CRC. The rate of adenoma detection was significantly higher in smokers than in those with a family history of CRC or IBD. The patient’s smoking status should be considered when individualizing recommendations for CRC screening and surveillance, particularly in patients who are at high risk.