Lymphatic vessel involvement is predictive for lymph node metastasis and an important prognostic factor in endometrial cancer.

Background: Lymphovascular space involvement is reported to be an important risk factor in endometrial cancer. This study was conducted to evaluate the separate prognostic effects of lymphatic invasion and venous invasion on the outcomes of patients with endometrial cancer.

Methods: From 2006 to 2013, 189 histologically confirmed endometrial cancer patients were examined. To study the venous invasion (v) of the endometrial cancer, Victoria blue-H&E staining-which positively stains the elastic fibers of vessels-was performed. Immunohistochemical staining with D2-40 was used to study the lymphatic invasion (ly) of the endometrial cancer.

Results: The median age of the patients was 57 (range 25-84) years. ly(+) and/or v(+) patients were significantly more likely to present an advanced cancer stage, G3 tumor, and deep myometrial invasion than ly(-)/v(-) patients. The incidence of lymph node metastasis was high in ly(+) patients, and that of ovarian metastasis was high in v(+) patients. Lymphatic vessel invasion was significantly correlated with regional lymph node metastasis. We found a significantly higher incidence of distant metastasis in ly(+) patients. Most recurrences in ly(+)/v(-) patients occurred in lymph nodes, while those in ly(+)/v(+) patients occurred mainly at distant organs. Finally, the prognosis was significantly poorer for ly(+) patients, in whom lymphatic invasion was an independent prognostic factor along with distant metastasis.

Conclusions: Our study suggests that by separately evaluating lymphatic invasion and blood vessel invasion in endometrial cancer cases, useful information for predicting lymph node metastasis and recurrence sites as well as prognostic information can be obtained.