Sentinel lymph node biopsy in endometrial cancer: description of the technique and preliminary results

Objective: To measure the feasibility of sentinel lymph node technique in endometrial cancer. Material and Methods: The study was designed as a prospective non-randomized case-control trial. Between 2010-2011, in Istanbul University, Istanbul Medical Faculty, Gynecologic Oncology department, 26 patients who were preoperatively evaluated as endometrial cancer enrolled in the study. Patients' detailed informed consent and ethics committee approval were obtained. Sentinel lymph node (SLN) detection rate was determined as the primary outcome. Sensitivity, specificity, positive and negative predictive values and particularly false negative results were determined as secondary outcomes. As a technique of SLN, injection of methylene blue to the subserosal myometrium of the uterine fundus via 5 cc syringe following peritoneal aspiration cytology procedure was obtained. Surgery was made after injection for an average of 5 minutes due to the physiological spread of the blue dye. Then, the standard protocol of hysterectomy was performed and the retroperitoneum was opened to perform lymphadenectomy. The presence of lymph node regions, and presence of a sentinel node was recorded on the trial record form. Positive staining nodes were sent separately for pathological examination. In the course of the study due to insufficient rate of staining, the technique has been changed to cervical and multiple uterine injections. Results: As the primary outcome, an SLN positivity rate of 23% in 6 patients with a total of 8 lymph nodes were found. The remarkable finding was that in the first technique, the rate was 1/16 (6%), while the second technique, 5/10 (50%), respectively. The difference is statistically significant (p=0.001). In endometrial cancer stage I and II, secondary outcomes for sensitivity, specificity, positive predictive value, negative predictive value were 23%, 0%, 100%, 43%, respectively. Because there were no metastatic lymph nodes found, false negative rate was 0%. Conclusion: SLN approach is not valuable enough to eliminate the need for lymphadenectomy. On the other hand, it facilitates scanning micrometastases and ultrastaging, while its clinical value has not yet been established. However, according to the recent pilot studies, it provides a means for assessing micrometastases for the medium-risk group for local recurrence.