Approximately 20% of patients with clinical stage I endometrial cancer will have lymph node metastases on comprehensive surgical staging. Evaluations of large clinical databases have suggested that there is improved survival with lymphadenectomy with greatest benefit associated with larger yields of lymph nodes at the time of surgery. However, randomized controlled trials from Europe have shown no survival benefit among patients who have undergone pelvic lymphadenectomy. However, were these studies appropriately designed and powered to answer the question definitively? Perhaps the most important role of lymphadenectomy is in its ability to tailor adjuvant therapy: ensuring those with systemic disease receive systemic therapy and avoiding the unnecessary prescription of whole pelvic radiation to unstaged patients. SLN biopsy may offer an alternative to comprehensive lymphadenectomy that preserves the informative role lymph node histology provides, while minimizing the immediate and long term risk to the patient of a lymphadenectomy.

In this lecture we will explore the variety of techniques available for SLN mapping in endometrial cancer. We will discuss the dosing, benefits and pitfalls of different tracers (blue dyes, radiolabelled colloids and ICG). We will also explore the controversy behind injection sites (cervical, versus endometrial, versus serosal). Finally we will discuss the definitions of metastatic volume to the lymph nodes, and the questions that loom over the clinical significance of micro metastatic lymph node volume. At the end of this lecture, we will propose algorithms for safely employing SLN mapping in endometrial cancer, and provide a suggested method to proceed from counseling, to tracer choice and administration, to pathology review and determination of adjuvant therapy.