Prognostic Value of Separate Extramural Vascular Invasion Reporting in Operative Samples of Rectal Cancer: Single-Institutional Experience

Background/Objectives: Vascular invasion, especially extramural vascular invasion (EMVI) has emerged as prognostic parameter for rectal cancer (RC) in recent years. Prediction of reccurence and metastases development poses a significant challenge for oncologists, needing markers for prediction of adverse outcome. The aim of this study was to examine the prognostic significance of pathohistologically detected EMVI in untreated rectal cancer and its implications in separate reporting. Methods: We examined 100 untreated RC patients who underwent curative resection from January 2016 to June 2018 with follow up of 5 years. Patients were divided in equal EMVI- and EMVI+ groups based on histological re-examination of HE stained postoperative surgical samples. Results: The presence of EMVI within the selected cohort was significantly associated with female gender, T3/T4 and N1/N2 post-operative stages, positive lymph nodes, lymph node ratio LNR2 and LNR3 groups, abundant tumor-infiltrating lymphocytes, positive lympho-vascular invasion (LVI), perineural (PNI), and circumferential resection margin (CRM) (p0.05 in all tests). Within EMVI+ patients, local recurrences and/or metastases, and death outcomes were more frequent events (p=0.029 and p=0.035, respectively), while survival analyses revealed that EMVI+ patients had significantly shorter overall survival (OS, p=0.040) and disease-free survival (DFS, p=0.028). Concerning LVI, differences in OS between LVI+ and LVI- patients were not statistically significant (p=0.068), while LVI+ patients had significantly shorter DFS (p=0.024). Moreover, univariate COX regression analysis demonstrated the negative impact of EMVI on OS (HR: 2.053, 95% CI: 1.015-4.152; p=0.045) and DFS (HR: 2.106, 95% CI: 1.066-4.870; p=0.038), which was not the case for LVI+ RC patients. Conclusions: Obtained results strongly suggest significance of separate reporting of EMVI from lympho-vascular invasion, as it is potentially a surogate marker for adverse prognosis and outcome.