ORIGINAL ARTICLE Higher adenoma recurrence rate after left- versus right-sided colectomy for colon cancer Lorenzo Fuccio, MD, 1 Cristiano Spada, MD, PhD, 2 Leonardo Frazzoni, MD, 1 Silvia Paggi, MD, 3 Giovanna Vitale, MD, 2 Liboria Laterza, MD, 1 Alessandro Mussetto, MD, 4 Fabiola Rojas, MD, 5 Franco Radaelli, MD, 3 Cesare Hassan, MD, PhD, 2 Lucio Petruzziello, MD, 2 Marzio Frazzoni, MD 6 Bologna, Rome, Como, Ravenna, Modena, Italy Background: Patients with history of colonic resection for cancer have an increased risk of the development of metachronous malignant and premalignant lesions. Scanty data are reported on detection rates of premalignant lesions during colonoscopy surveillance in this setting. Objective: To assess the risk of metachronous precancerous lesions developing in patients with previous colonic surgery for cancer according to the resection type. Design: Retrospective study. Setting: Two academic centers in Italy. Patients: A total of 441 patients; 256 with previous left-sided colectomy (LCR) (LCR group) and 185 with previous right-sided colectomy (RCR) (RCR group). Interventions: Second surveillance colonoscopy. Main Outcome Measurements: Polyp and adenoma detection rates. Results: At least 1 adenoma was diagnosed in 76 of 256 patients (30% adenoma detection rate) and in 35 of 185 patients (19% adenoma detection rate) in the LCR and RCR groups, respectively (P Z .014), yielding an odds ratio of 1.83 (95% confidence interval, 1.16–2.89). Corresponding figures for the polyp detection rate were 39% and 25%, respectively (P Z .002; odds ratio 1.97; 95% confidence interval, 1.30-3.00). Limitations: Retrospective study with colonoscopy baseline information missing. Conclusions: Patients who have undergone LCR are at higher risk of the development of adenomas than those who have undergone RCR. If this result is confirmed by large prospective studies, surveillance programs could be targeted according to the type of colonic resection, with longer intervals for patients with previous RCR compared with LCR. (Gastrointest Endosc 2015;-:1-7.) Today, the 5-year survival rate for colorectal cancer (CRC) is approximately 65%, and it is progressively increasing because of the recent improvement in CRC early detection and treatment. 1 Surgical resection has a pivotal role in the management of patients with CRC and represents the primary treatment for the approximately 80% of those with nonmetastatic disease. Surveillance colonoscopy is highly recommended by major international scientific societies with the intent of either detecting anastomotic recurrence at an early, Abbreviations: ADR, adenoma detection rate; CI, confidence interval; CRC, colorectal cancer; LCR, left-sided colectomy; OR, odds ratio; PDR, polyp detection rate; RCR, right-sided colectomy. DISCLOSURE: All authors disclosed no financial relationships relevant to this article. Copyright ª 2015 by the American Society for Gastrointestinal Endoscopy 0016-5107/$36.00 http://dx.doi.org/10.1016/j.gie.2014.12.057 Received September 18, 2014. Accepted December 28, 2014. Current affiliations: Department of Medical and Surgical Sciences, S. Orsola-Malpighi Hospital, University of Bologna, Bologna (1), Digestive Endoscopy Unit, Catholic University, Rome (2), Division of Endoscopy, Valduce Hospital, Como (3), Division of Endoscopy, S. Maria delle Croci Hospital, Ravenna (4), Division of Oncology, S. Orsola-Malpighi Hospital, University of Bologna, Bologna (5), Digestive Pathophysiology Unit, Baggiovara Hospital, Modena (6), Italy. Reprint requests: Lorenzo Fuccio, MD, Department of Medical and Surgical Sciences, S. Orsola-Malpighi Hospital, University of Bologna, Via Massarenti 9, 40136, Bologna, Italy. www.giejournal.org Volume -, No. - : 2015 GASTROINTESTINAL ENDOSCOPY 1