James Franklin MA, MBBS, Abstract Co-Author: Nothing to Disclose

Fergus Vincent Gleeson MBBS, Abstract Co-Author: Alliance Medical Ltd Consultant

Ewan Mark Anderson MBBCh, Presenter: Nothing to Disclose

Macroscopic extramural vascular invasion (mEMVI) can be detected on staging MRI for rectal carcinoma and mEMVI has been associated with synchronous metastatic disease. The aim of this study was to assess the prognostic significance of mEMVI on subsequent metastatic relapse at 3 years.

30 patients with locally advanced rectal cancer were recruited into this prospective study and underwent staging MRI including an axial small field of view (sFOV) T2W (MRI (TR/TE 3620/85ms, 20cm FOV with a matrix of 384x256, slice thickness 3mm, spacing 0.3mm) at 1.5T (GE Signa, GE Healthcare, Milwaukee, US). Patients with synchronous metastatic disease at presentation or metastasis-free follow-up for less than 3 years were excluded from the analysis. The presence of distant metastatic disease at 3 years was based on all available follow-up imaging including contrast-enhanced CT and MRI and FDG-PET/CT where available. The presence or absence of mEMVI was recorded, in addition to T- and N-staging, depth of invasion into the mesorectal fat (subdivided into >5mm and <5mm) and peritoneal invasion. Chi-squared tests were used to test the association of each feature with metastasis-free survival (MFS) at 3 years.

8 patients were excluded form the analysis. 22 patients formed the study group, in whom 11 (50%, 95% CI 31-69%) developed metastatic disease at 3 years. 17 (77% 95% CI 57-90%) patients had evidence of mEMVI on staging MRI. 0/5 of those without mEMVI and 11/17 with mEMVI developed metastatic disease at 3 years (0% vs 64.7%, p=0.011). The other features were not associated with MFS.

The presence of EMVI on staging pelvic MRI for rectal cancer is associated with a significantly higher risk of metastatic relapse at 3 years.

The presence of adverse imaging features for metastatic relapse may be used to stratify patients with rectal cancer who will benefit from adjuvant systemic therapy.

Franklin, J, Gleeson, F, Anderson, E, The Prognostic Significance of Macroscopic Extramural Vascular Invasion on MRI in Patients with Locally-advanced Rectal Cancer.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14013362.html