Objective To evaluate the relationship between pelvic/para-aortic sentinel lymph node status and two different injection sites of 99m-technetium (^99mTc)-labeled phytate in patients with endometrial cancer.

Methods This was a randomized controlled trial involving 81 patients with endometrial cancer. In the cervical group (n=40), injections of ^99mTc were performed at the 3 and 9 o’clock positions of the uterine cervix. In the endometrial group (n=41), ^99mTc was injected into the fundal endometrium using a transcervical catheter. Sentinel lymph nodes were detected through pre-operative lymphoscintigraphy and intra-operatively using a handheld gamma probe. All patients underwent complete pelvic and para-aortic lymphadenectomy procedures. Pathologic ultra-staging was performed with immunostaining for cytokeratin in sentinel lymph nodes after routine hematoxylin and eosin histological examinations. The primary endpoint was the estimation of detection rates, sensitivity, false-negative rates, negative predictive value, and analysis of the distribution of pelvic and para-aortic sentinel lymph nodes.

Results The rate of detection of at least one sentinel lymph node, sensitivity, and the negative predictive value was 80%, 66.6%, 96.6% for the cervical group and 85%, 66.6%, 96.9% for the endometrial group, respectively. False-negative sentinel lymph nodes were detected in one patient from each group . There was no significant difference between the groups in terms of total sentinel lymph node count, sentinel pelvic lymph node count, and pelvic bilaterality, but the para-aortic sentinel lymph node count was significantly higher in the endometrial group (p<0.001). Ultra-staging examination of the pelvic sentinel lymph nodes revealed isolated tumor cells in one patient from each group.

Conclusion Transcervical endometrial tracer injection in endometrial cancer revealed similar pelvic but significantly higher para-aortic sentinel lymph node detection.