MRI-detected extramural vascular invasion (mrEMVI) as the best predictive factor to identify candidates to total neoadjuvant therapy in locally advanced rectal cancer.

Abstract

Chemotherapy in locally advanced rectal cancer (LARC) is shifting from an adjuvant setting to a total neoadjuvant therapy (TNT) strategy, that relies on distant metastases (DM) risk prediction. This study aims to assess the accuracy of magnetic resonance imaging-detected extramural vascular invasion (mrEMVI) as predictive factor for DM in LARC, compared with other MRI-detected and pathologic factors. This retrospective single-center study analyzed data extracted from a series of consecutive patients curatively resected for rectal cancer at Mauriziano Hospital in Turin (Italy) from January 2013 to December 2018. Data from 69 patients were analyzed. MrEMVI was detected in 31 (44.9%) cases. Median follow-up was 39.9 months. DM and local recurrence occurred in 19 (27.5%) and 4 (5.8%) patients. One- and 3-year cumulative incidence of DM were 32.3% (95% confidence interval [CI]: 0.17-0.49) and 56.8% (95% CI: 0.35-0.74) in the mrEMVI-positive group and 5.4% (95% CI: 0.01-0.16) and 14.0% (95% CI: 0.05-0.27) in the mrEMVI-negative group (log-rank test, p < 0.001). In the multivariate analysis of MRI factors, mrEMVI was the only independent predictor of DM (HR: 3.59, CI: 1.21-10.69, p = 0.02). This study confirmed that mrEMVI is a powerful predictor of DM in LARC. It should be routinely reported and considered during multidisciplinary care strategy planning.