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Gastrointestinal Imaging

E2549. The Role of MRI as a Predictor of Distant Recurrence in Rectal Cancer

Torres C1,  Valadão M1,  Ferreira C1,  Brandt C.1 1. National Institute of Cancer, , Rio de Janeiro, Brazil

Address correspondence to C. Brandt (camila_brandt@hotmail.com)

Objective: Our objective is to evaluate the correlation between the presence of extramural vascular invasion (EMVI) by MRI with the development of distant metastases in patients with locally advanced extraperitoneal rectal adenocarcinoma.

Materials and Methods: As part of this project, a randomized prospective clinical trial in which two systemic therapies were compared in the neoadjuvant treatment of advanced adenocarcinoma of extraperitoneal rectum in combination with radiation therapy, 60 patients underwent pelvic MRI examination for local staging before and after neoadjuvant treatment and underwent CT scanning for staging. The EMVI was checked on T2-weighted sequences for the presence of tumor signal expanding and changing the contour of the vessel as well as nodules with irregular contour in vascular topography. We evaluated the association between the presence of EMVI in patients before and after chemoradiation therapy (CRT) with metastasis. Metastasis-free survival curves were estimated using the Kaplan-Meier method according to the presence of EMVI on MRI before and after CRT, and the comparison between them was done by Log-rank test. The distant recurrence risk was estimated by multiple Cox regression adjusted for local staging by MRI (T and N) and age.

Results: After median follow-up of 39.3 months, we observed an increased risk of metastasis (hazard ratio, 3.2; 95% CI, 1.0–10.3; p = 0.051) and reduced metastasis-free survival from 33.77 to 25.17 months (p = 0.041) in patients with EMVI on MRI before CRT when compared with patients without EMVI. There was no statistically significant association between metastasis onset and the presence of EMVI on MRI after CRT.

Conclusion: The presence of EMVI on MRI before CRT is associated with increased risk of distant metastases.