Magnetic Resonance Imaging Value to Predict Pathologic Staging in Locally Advanced Rectal Cancer After Neoadjuvant Chemoradiation

Abstract

Aim: This study was designed to evaluate the role of magnetic resonance imaging (MRI) on preoperative restaging of locally advanced rectal cancer after neoadjuvant chemoradiotherapy (CRT), in order to facilitate individualization of surgical management. Method: We analyzed 117 patients who had received neoadjuvant CRT, underwent a MRI before and after CRT. All patients underwent restaging MRI followed by surgery after the end of CRT. The primary end point of this study was to estimate the accuracy of post-CRT MRI as compared with pathologic staging. Results: Pathologic T classification matched the post-CRT MRI findings in 44 (37.6%) of 117 patients. Sensitivity in T0, T1, T2, T3 and T4 was 23.8%, 16.7%, 25.6%, 48.9% and 83.3% respectively. Specificity in T0, T1, T2, T3 and T4 were 87.5%, 93.7%, 79.5%, and 64% and 88.3% respectively. Sensitivity in N0 and N1 were 82% and 20% respectively. Specificity was 88% in N0 and 87% in N1. Fifty two (44.4%) of 117 patients were downstaged in T classification. Pathologic N classification matched the post-CRI MRI findings in 73 (62.4%) of 117 patients. Twenty one (17.9%) were overstaged in N classification. Twenty seven (23%) of 117 patients who had been down staged on MRI after CRT were confirmed on the pathological staging with same stage (T and N). 17p with ypT0 were correlated with MRI after CRT in 5 patients (4.3%). Conclusion: MRI has low accuracy for restaging locally advanced rectal cancer after preoperative CRT so it is currently not consistent enough for clinical application.

Keywords

• MRI
• neoadjuvant chemoradiotherapy
• prediction