Correlation analysis between MRI parameters and prognosis in locally advanced rectal cancer patients receiving chemoradiotherapy

Objective: To investigate the relationship between MRI parameters and clinical prognosis before and after chemoradiotherapy in patients with locally advanced rectal cancer. Methods: Clinical and follow-up data of 96 patients with locally advanced rectal cancer who were initially treated in the Cancer Hospital of Chinese Academy of Medical Sciences from 2015 to 2017 were retrospectively analyzed. All patients received preoperative chemoradiotherapy, followed by delayed radical surgery at 6-13 weeks after radiotherapy. MRI assessment was performed twice around radiotherapy which were within 4 weeks before the treatment and 4-8 weeks after it. Correlation analysis was utilized to determine the association between MRI assessment and 3- year disease-free survival (DFS). Results: Of the all patients, 80 (83%) had T₃ stage, 16 (17%) had T₄ stage, 14 (15%) had N₀ stage, and 82 (86%) had N_1-2 stage. Among them, 69 (72%) and 58 (60%) patients were positive for MRF and EMVI. The median dose of radiotherapy was 50 Gy, and all patients were sensitized by simultaneous capecitabine. After chemoradiotherapy, T-down stage rate of the whole group was 24%, and 50% for the N-downstage rate. The MRF-and EMVI-positive rates were significantly decreased to 37% and 27% after chemoradiotherapy (both P < 0.001). Univariate and multivariate analysis showed that N staging and EMVI status change were significantly correlated with the 3-year DFS. Conclusion: MRI after concurrent chemoradiotherapy reveals that positive EMVI throughout the treatment and N₁-N₂ staging are poor prognostic factors of DFS, suggesting the need for improving the treatment. (authors)