Risk factors for lymph node metastases in women with endometrial cancer: A population-based, nation-wide register study-On behalf of the Swedish Gynecological Cancer Group.

The role of lymphadenectomy in the management of early endometrial cancer remains controversial. In the recent ESMO-ESGO-ESTRO guidelines, lymphadenectomy is recommended for patients with endometrioid adenocarcinoma Grade 3 with deep myometrial invasion, but complete agreement was not achieved. In Sweden, DNA aneuploidy has been included as a high-risk factor. The aim of our study was to evaluate the impact of tumor histology, FIGO grade, DNA ploidy and myometrial invasion (MI) on occurrence of lymph node metastasis (LNM) in patients with endometrial cancer. The study design is a retrospective cohort study based on prospectively recorded register data. Endometrial cancer patients registered in the Swedish Quality Registry for Gynecologic Cancer 2010-2015 with FIGO Stages I-III and verified nodal status were included. Data on DNA ploidy, histology, FIGO grade and MI were included in multivariable log-binomial regression analyses with LNM as dependent variable. 1,165 cases fulfilled the inclusion criteria. The multivariable analyses revealed increased risk of LNM in patients with tumors with MI ≥ 50% (risk ratio [RR] = 4.1; 95% confidence interval [CI] 3.0-5.6), nonendometrioid compared to endometrioid histology (RR 1.8; CI 1.4-2.4) and FIGO Grade 3 compared to Grade 1-2 tumors (RR 1.5; CI 1.1-2.0). No statistically significant association between DNA ploidy status and LNM was detected. This population-based, nation-wide study in women with endometrial cancer confirms a strong association between MI ≥ 50%, nonendometrioid histology and FIGO Grade 3, respectively, and LNM. DNA ploidy should not be included in the preoperative decision making of removing nodes or not.