Different adenoma recurrence rates on surveillance colonoscopy in patients with right- or left-sided colonic cancer after curative colectomy

Abstract

Background: Patients with history of colorectal cancer (CRC) are at increased risk of developing metachronous adenoma even after colectomy. We aim to determine the prevalence and factors associated with the development of adenoma on surveillance colonoscopy in patients with previous colonic resection for CRC. Methods: Consecutive patients with CRC who had undergone surgical resection in our hospital between January 2001 and December 2002 were identified. Patients were included for analysis only if they had undergone surgery for curative intent and had a clearing colonoscopy either performed before surgery or within 6 months after the operation. Patients with familial colorectal cancer syndrome (familial adenomatous polyposis, hereditary non-polyposis colorectal cancer syndrome), subtotal or total colectomy, and inflammatory bowel syndrome were excluded. Patient's baseline characteristics, tumor locatio ns, type of surgical intervention, drug use (aspirin and non-steroidal anti-inflammatory drugs (NSAIDs)) and surveillance colonoscopy findings were retrieved. Right-sided CRC (R-CRC) was defined as cancer proximal to the splenic flexure and left-sided CRC (L-CRC} included all other distal cancers. Results: 592 patients underwent surgical resection for CRC during the study period and 329 patients (92 patients with R-CRC and 237 with L-CRC) fulfilled our inclusion criteria. Among them, 63 (68.5%} patients with baseline R·CRC and 174 (73.4%) patients with baseline L-CRC had at least one surveillance colonoscopy after bowel resection, with a total of 330 colonoscopies performed. The rates of metachronous lesions amongst those who had surveillance colonoscopy were shown in Table. Multivariate analysis showed that the following factors were independently associated with met achronous adenoma: L-CRC at baseline (OR: 3.52, 95% Cl, 1.42-8.73, p<0.01), patient's age (OR: 1.05, 95% Cl1.02-1.09; p<O.Ol) and male sex (OR 2.95, 95% Cl 1.40-6.22; p<O.Ol). Conclusion: Patients who had surgery for L-CRC have a higher chance of developing metachronous polyps and adenoma than those with R-CRC. Our findings may imply a need to have a different surveillance strategy for patients with L-CRC or R-CRC.