Improving lymph node harvest in colorectal cancer by intra-arterial injection of methylene blue: a randomized trial

Background: Prognosis in colorectal carcinoma is related to the state of lymph node involvement. Myriad studies demonstrate that both survival and prognosis are significantly influenced by the number of lymph nodes harvested, particularly in node-negative disease. Aim: The aim of this study was to evaluate the usefulness of injecting methylene blue into the main artery/ arteries of resected colorectal specimens in terms of the total number of lymph nodes identified. Patients and methods: The study included 54 patients randomly divided into two groups: group 1 (26 patients), in which resected specimens of colorectal carcinoma were injected with methylene blue, and group 2, in which no injection was carried out. Results: The total number of lymph nodes per patient in group 1 was 19.5 (17–39) [median (range)] and that in group 2 was 16.5 (8–19). The difference was statistically highly significant (P 0.001). We also noticed that the best improvement in lymph nodes harvest was among the very small and small lymph nodes. Conclusion: Methylene blue injection into the main artery/arteries is an effective and simple method for improving the lymph node harvest in resected specimens of colorectal carcinoma.