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

Background and objectives: 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.

Methods: 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.

Results: 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).

Conclusions: 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.