Blood Vessel Invasion Is an Independent Prognostic Factor in Endometrial Endometrioid Carcinoma Compared to Lymph Vessel Invasion and Myometrial Invasion Pattern

Simple Summary: Endometrial endometrioid carcinoma (EEC) is generally considered to have a good prognosis. However, a subset of patients die of their disease. For this reason, it is essential to reveal and define all prognostic factors that can guide optimal treatment. Because lymphovascular space invasion (LVSI) is now related to staging, and blood vascular invasion seems to be more important than lymphovascular invasion, it could be important to encourage pathologists to distinguish between the two. The morphologic pattern of myometrial invasion may also be related to biological behavior. Myometrial invasion with an infiltrative pattern is associated with advanced-stage LVSI and recurrence. A specific pattern of myometrial invasion characterized by microcystic, elongated, and fragmented (MELF) glands is known to be associated with LVSI and lymph node metastases. This study investigated the relationship between these three closely related parameters, particularly the importance of blood vessel invasion (BVI), lymphatic vessel invasion (LVI), and MELF invasion as prognostic factors for endometrial cancer. This may be of great importance for the therapeutic approach in EEC. We studied 115 cases of EEC diagnosed on hysterectomy specimens. Double immunohistochemical staining (D2-40/CD31) was performed in all 115 cases to show LVI and BVI on the same slide. MELF pattern invasion was present in 24/115 (21%) cases. MELF-positive tumors had a higher frequency of LVI than MELF-negative tumors (58% and 23%, respectively); the frequency of BVI was twice as high in MELF-positive tumors in comparison to MELF-negative tumors (25% and 12%, respectively). These differences were significant (p < 0.0001). All tumors with positive BVI also had a concomitant LVI. The presence of MELF invasion had no impact on overall survival, confirming previous studies. 5-year survival rates were almost equal in cases with negative LVSI and cases with positive isolated LVI (98% vs. 97%). However, in cases where BVI was also present, the 5-year survival rate was significantly lower, 63% (p < 0.0001). Furthermore, BVI proved to be an independent prognostic factor for overall survival, disease-free survival, and recurrence in the multivariate analysis. In conclusion, MELF pattern invasion is a good predictor of lymphatic and blood vessel invasion but has no prognostic value. Our results suggest that BVI in EEC has greater clinical value than isolated LVI or myometrial invasion patterns, and the therapeutic approach should be guided by BVI presence. Therefore, we hope this study will promote the routine evaluation of BVI in the context of EEC diagnostic procedures.