The prognostic significance of MRI-detected extramural venous invasion in rectal carcinoma

AimTo assess whether there is a significant difference in the incidence of patients with metastases of rectal carcinoma at 1 year follow-up between magnetic resonance imaging (MRI)-detected extramural venous invasion (EMVI) and those without.Materials and methodsA search of our institution's cancer registry revealed 788 patients with rectal carcinoma between January 2007 and April 2012. Those who were initially staged using MRI and computed tomography (CT) chest/abdomen/pelvis, and followed-up with a CT chest/abdomen/pelvis examination at 1 year were included in this retrospective study. Patients with synchronous metastases were excluded, leaving a cohort of 202 cases. Two consultant radiologists reviewed all MRI images and gave a consensus opinion regarding EMVI grade and vessel size involved. All CT images were reviewed for metastases. Results were analysed using chi-squared and Fisher's exact tests.ResultsThere were 53 cases (26.2%) of EMVI-positive rectal carcinoma. Of the patients with EMVI, 24.5% developed metastases at 1 year follow-up, compared to 6.7% of those without. There is a significant difference in prognosis between those patients with and those without MRI-detected EMVI (χ2 = 12.29, p < 0·001). Those with EMVI have a 3.7 times increased relative risk of developing metachronous metastases within 1 year of diagnosis.ConclusionMRI-detected EMVI-positive rectal carcinomas are associated with an increased risk of metachronous metastases within 1 year of diagnosis. Currently, EMVI status does not directly influence the initial management of rectal carcinoma. This available and potentially prognostic feature could be used to guide treatment pathways to increase disease-free survival.