Endoluminal ultrasound versus magnetic resonance imaging in assessment of rectal cancer after neoadjuvant therapy

BACKGROUND: Accurate rectal tumor staging guides the choice of treatment options. EUS and MRI are the main modalities for staging. AIM OF THE WORK: To compare the performance of EUS and MRI for loco-regional staging of anorectal cancer after neo-adjuvant therapy. METHODS: Seventy-three (37 male, 36 female) patients with rectal cancer after neo-adjuvant chemoradiotherapy were enrolled. Histopathological staging after surgery were used as reference for comparing the yield of loco-regional staging for EUS and MRI. EUS and MRI were done 1 month after completion of neo-adjuvant therapy. RESULTS: Regarding post-surgical T staging, eight patients had early tumor (T2 = 16 and T1 = 9) and thirty six were locally advanced (T3 = 36), while N staging, forty patients with negative nodes and 33 were positive (N1 = 22 and N2 = 11). Comparing EUS to MRI, it showed a higher sensitivity (95.7% vs. 78.7%), specificity (84.6% vs. 68.0%) and accuracy (91.8% vs. 75.3%) for staging early and locally advanced tumor. Also, it had a higher sensitivity (78.8% vs. 69.7%), specificity (75.0% vs. 65.0%) and accuracy (76.7% vs. 67.1%) for detection of lymph nodes. CONCLUSION: EUS appears to be more accurate than MRI in loco-regional staging of rectal carcinoma after neo-adjuvant therapy.