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

Objective: This study aimed to identify the impact of preoperative colonoscopic tattooing (PCT) on lymph node harvest in T1 colorectal cancer patients. Material and methods: 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. Results: 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 %). Conclusions: 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.