The effect of colonoscopic tattooing on lymph node retrieval and sentinel lymph node mapping

Background: In colorectal cancer (CRC), colonoscopic tattooing is performed to mark the tumor site before laparoscopic surgery. Objective: To determine whether colonoscopic tattooing can be used to refine staging accuracy by increasing the lymph node (LN) yield per specimen and to determine its accuracy as a sentinel LN procedure. Design: Retrospective, case-control study. All LNs were microscopically examined for the presence of carbon particles. Setting: A university hospital and a teaching hospital. Patients: A consecutive series of 95 tattooed patients who had surgery for CRC between 2005 and 2009. A series of 210 non-tattooed patients who had surgery in the same time period served as controls. Main Outcome Measurements: Total number of LNs retrieved, detection rate, and sensitivity of tattooing as a sentinel node procedure. Results: A higher LN yield was observed in patients with preoperative tattooing, median (interquartile range) 15 (10-20) versus 12 (9-16), (P = .014). In multivariable analysis, the presence of carbon-containing LNs was an independent predictive factor for a higher LN yield (P = .002). The detection rate was 71%, with a median of 5 carbon-containing LNs per specimen. If preoperative tattooing was used for sentinel node mapping, the overall accuracy of predicting LN status was 94%. In the 24 N1 cases, there were 4 false-negative procedures (sensitivity 83%). Limitations: Retrospective series. Conclusion: After tattooing of CRC, the LN yield was higher than in a control group, and it could be used as a sentinel node procedure with acceptable accuracy rates. Because LN yield and sentinel node mapping are associated with improved diagnostic accuracy of LN involvement, preoperative tattooing can refine staging. (Gastrointest Endosc 2012;76:793-800.)