Localizing colorectal cancer by colonoscopy

Hypothesis: Colonoscopic localization of colorectal carcinoma is frequently inaccurate and unreliable. Design: Consecutive case series. Setting: Tertiary care teaching hospital. Patients: Three hundred fourteen consecutive patients undergoing surgical resection for colorectal cancer from January 1, 2000, to December 31, 2003. Intervention: Surgical resection for colorectal cancer. Main Outcome Measure: Incidence of erroneous site localization. Results: Two hundred thirty-six patients had complete endoscopic, pathologic, and operative records. Colonoscopy was inaccurate for tumor localization in 49 cases (21%). In 27 (11%) of these cases, a different procedure was required than initially planned; in an additional 10 cases (4%), the surgical approach required modification. Inaccurate localization was associated with previous colorectal procedures on both univariate analysis (odds ratio, 3.94; 95% confidence interval, 1.50-10.32; P <.005) and multivariate analysis (odds ratio, 4.47; 95% confidence interval, 1.64-12.08; P=.003). Having the colonoscopy performed by a surgeon trended toward protection from error on multivariate analysis (odds ratio, 0.47; 95% confidence interval, 0.20-1.08; P=.07). Age, sex, diverticular disease, endoscopist volume and years of training, and bowel preparation had no significant effect. Conclusions: Colonoscopy has a considerable error rate for localization of colorectal cancer, especially when previous colorectal procedures have been performed. Adjunctive localizing techniques, such as endoscopic tattooing, should be strongly considered.