A Prospective Cohort Study on Neck Lymph Node Mapping in Oral Cancers Using Methylene Blue Dye

In the current scenario, the management of N0 neck in early-stage oral cancer is debatable, whether or not they should undergo elective neck dissection. Most of the time these patients are either over-treated or under-treated. Sentinel lymph node (SLN) biopsy is a good option to identify occult LN in this cohort of patients for guiding neck dissection. With a focus on SLN biopsy using methylene blue dye, this study aims to evaluate its feasibility and accuracy in node-negative oral squamous cell carcinoma. A prospective observational study was conducted involving operable squamous cell carcinoma patients with clinically and radiologically node-negative neck. Methylene blue was injected in the peritumoral area and after that SLN was identified and then neck dissection was completed. Of 47 patients, SLN was identified in 82.98%, with 53.85% having more than two SLN. Common locations were in levels IB, IA and IIA. Occult metastasis was observed in 12.82% of cases, predominantly in T2 patients. Sensitivity, specificity and NPV were 50%, 100% and 88.89% respectively. The study affirms the feasibility and accuracy of methylene blue-assisted SLN biopsy in oral cancer. Despite a high detection rate, methylene blue dye alone should not be used for SLN identification in oral cavity cancer. However, it can be used as an adjunct of lymphoscintigraphy to increase the yield of the procedure. Multi-institutional trials with larger cohorts may provide valuable insights and more information for comprehensively addressing the limitations of this technique and its broader applicability in decision-making, particularly in resource-constrained countries like India where lymphoscintigraphy is not readily accessible.