Preoperative endoscopic tattooing and improved lymph node retrieval in colorectal cancer: a case-control study

Background and aim: Many factors may affect the total number of lymph nodes examined in surgical specimens including surgical technique and methodology of nodes evaluation. Lymph node retrieval has recently been shown to be facilitated in colorectal cancer specimens with preoperative endoscopic tattooing, as the nodes may be more easily identified. The aim of study was to confirm such evidence in an Italian tertiary care center. Material and methods: All patients undergoing an elective colonic or rectal resection for possible cancer between January 2009-December 2011 at the Department of Surgery of the S. Anna Hospital in Ferrara (Italy) were included and divided into two groups: 107 patients in whom India ink tattooing was performed at preoperative colonoscopy (tattooed group) and 143 in whom it was not (control group). The primary outcome measures were: total number of lymph nodes harvested per specimen, number of adequate lymphadenectomies (≥12 nodes) performed. All factors known to influence lymph node retrieval from colorectal specimen were specifically evaluated. Rectal cancers were analyzed together and separately from colonic cancers. Results: Tattooed patients with colonic cancer were slightly younger than controls (69.5±11.6 years vs 72.9±9.6 years, p=0.02). Tumor size for colonic cancer was less in the tattooed group compared to controls (4.6±2.4 cm vs 5.4±2.8 cm, p=0.03). Besides that, the study groups were comparable regarding age, gender, BMI, tumor location and size, TNM staging, DNA microsatellite instability–high status and preoperative chemoradiation therapy. No difference could be detected neither in the median number of lymph nodes retrieved 16.0 (4–46) vs 17.0 (3–60), p=NS) nor in the number of adequate lymphadenectomies (78% vs 83%, p=NS) between the tattooed and control groups. There was no difference in the number of both lymph nodes harvested and adequate lymphadenectomies among high-volume and low-volume surgeons. Pathologists dedicated to gastrointestinal diseases showed a higher number of lymph nodes retrieved as well as adequate lymphadenectomies in in both study groups compared to non-dedicated pathologists. Conclusions: This study does not confirm that preoperative ink tattooing improves the lymph nodes yield from colorectal cancer specimen. Further studies are therefore needed to determine if colonscopic tattooing canrefine staging. The pathologist is confirmed as a fundamental element.