MRI morphologic and clinicopathologic characteristics for predicting outcomes in patients with locally advanced rectal cancer.

Purpose: The aim of this study was to investigate the value of MRI morphologic and clinicopathologic factors for predicting 3-year disease-free survival (DFS) in patients with locally advanced rectal cancer (LARC).

Method: In this retrospective study, pre- and post-neoadjuvant chemoradiotherapy (nCRT) MRI morphologic (e.g., pre-nCRT MRI-detected extramural venous invasion) and clinicopathologic variabilities (e.g., pathological complete response) were evaluated in all patients. Three-year DFS was estimated using Kaplan-Meier product-limit method, and Cox proportional hazards models were used to determine associations between morphologic or clinicopathologic variabilities and survival outcomes.

Results: A total of 115 patients (39 females and 76 males; median age, 54 years; age range, 28-82 years) with LARC treated with nCRT were enrolled. With a median follow-up of 48.0 months, the 3-year DFS was 79.0% for all patients. During follow-up, 18 patients died, 28 patients experienced relapse (26 distant, one local, and one both), and 69 patients were censored. MRI-detected extramural venous invasion (mrEMVI) was the only significantly independent factor of long-term survival, while HR was 2.308 (95% CI 1.151-4.629, P = 0.018) on univariate and 2.495 (95% CI 1.243-5.012, P = 0.010) on multivariate analysis. The 3-year cumulative survival rate in patients with mrEMVI negativity compared with positivity were 86.6% versus 65.0% (P = 0.015), respectively.

Conclusion: In conclusion, pre-nCRT mrEMVI status was the independent significant risk factor for long-term outcomes in LARC patients treated with nCRT, while the other morphologic and clinicopathologic characteristics were not related to the patient survival.