Objective To establish new criteria for the omission of lymphadenectomy in patients with endometrioid carcinoma.

Methods  We retrospectively reviewed 185 cases of histologically confirmed endometrioid carcinoma by hysterectomy at Jichi Medical University Hospital between January 2006 and December 2011. We reviewed patient medical records to detect risk factors for lymph node metastasis to identify the optimum criteria for lymphadenectomy omission.

Results Univariate analysis revealed risk factors for lymph node metastasis to be a large tumor size (volume index ≥40 cm³) (p<0.0001), tumor diameter >2 cm (p=0.0003), myometrial invasion ≥50% based on pre-operative MRI (p=0.0366), elevated serum CA125 (pre-menopausal value ≥70 U/mL, post-menopausal value ≥25 U/mL) (p=0.0004), and lymphadenopathy on pre-operative CT scans (p=0.0002). Multivariate analysis indicated that tumor volume index, tumor diameter, elevated serum CA125, and CT scans positive for lymphadenopathy were independent risk factors for lymph node metastasis. Thus, we set tumor diameter >2 cm, elevated serum CA125, and CT scans positive for lymphadenopathy as risk factors. In cases with no risk factors, the rate of lymph node metastasis was 2.1%, which rose to 8.9%, 30.4%, and 58.3% for those with one, two, and three risk factors, respectively. The rate of para-aortic lymph node metastasis rose from 0% to 2.5%, 10.9%, and 41.7% among those with zero, one, two, and three risk factors, respectively.

Conclusions We propose that lymphadenectomy can be omitted in cases of endometrioid carcinoma that do not have any of the following risk factors: tumor diameter >2 cm, elevated serum CA125, and a CT scan positive for lymphadenopathy. We believe that these new criteria will limit inter-institutional differences as they are all objective factors. Further, they are useful in predicting lymph node metastasis, including para-aortic lymph node metastasis, based on the number of risk factors present.