Effect of preoperative colonoscopic tattooing on lymph node harvest in T1 colorectal cancer

This study aimed to identify the impact of preoperative colonoscopic tattooing (PCT) on lymph node harvest in T1 colorectal cancer patients. One hundred and forty-three patients were included who underwent curative resection and were diagnosed with T1 colorectal cancer. These patients were categorized into the tattooing group and the non-tattooing group depending on whether preoperative India ink tattooing was done. Clinicopathological findings and lymph node harvest were compared between the two groups. The median number of lymph nodes examined was 18 in the tattooing group and 13 in the non-tattooing group (p < 0.001). The rate of adequate lymph node harvest (retrieval of more than 12 lymph nodes) was higher in the tattooing group than that in the non-tattooing group (83.7 vs. 58.5 %, p = 0.002). The PCT was significantly associated with adequate lymph node harvest in multivariate analysis (hazard ratio, 3.8; 95 % confidence interval, 1.5-9.2; p = 0.003). Among the 40 patients who showed at least one carbon particle-containing lymph nodes, the positive lymph node rate was not different between carbon-containing LNs (0.9 %) and non-carbon-containing LNs (1.7 %). PCT was associated with higher lymph node yield in T1 colorectal cancer. It is questionable if tattooing has additional detection power as a sentinel lymph node mapping tool in T1 colorectal cancer.