Blue dye single labelling for colorimetric sentinel lymph node mapping in early endometrial cancer: A feasibility study

Background Surgical staging in endometrial cancer includes a systematic lymphadenectomy with significant morbidity, although its therapeutic role is unclear. Sentinel lymph node (SLN) study is a less morbid alternative to identify nodes most likely to be metastatic, permitting selective removal and thus reducing morbidity without compromising oncological safety. This study was done using blue dye single labelling to study the feasibility and utility in identifying SLN in early disease. Methods Twenty-two patients of early-stage low-risk disease during surgical staging underwent cervical injection of methylene blue, SLN mapping, and sampling as per the standard algorithm, followed by a systematic lymphadenectomy in all cases. SLN were submitted separately for ultrastaging (US). Results Twenty patients underwent the procedure, and SLN could be identified in 18 patients with an overall mapping rate of 90% with a bilateral mapping rate of 70%, and a negative mapping rate of 10%. 57 SLN were identified along with two suspicious non-sentinel nodes and 11 were metastatic on US with a sensitivity of 66.7% and NPV of 87.5%. All patients with metastatic nodes, however, could be identified by applying the standard SLN algorithm for sampling. Conclusion SLN mapping algorithm with blue dye single labelling in early endometrial cancer, by identifying LN most likely to be metastatic enabling their selective removal may help avoid routine lymphadenectomies without compromising oncological safety. The procedure is simple and can be practiced at all centres and can also aid pathologists by pinpointing the likely metastatic nodes after a selective or complete lymphadenectomy.