Endorectal Ultrasound Versus MRI for Lower and Middle Rectal Cancer Staging in Upfront Surgery: A Comparative Study.

Objectives: This study aimed to compare the results obtained by endorectal ultrasound (ERUS) and magnetic resonance imaging (MRI) with the pathologic staging of the operative specimen in patients with lower and middle rectal cancer not treated with neoadjuvant therapy and undergoing surgery. Methods: From 2011 to 2022, all the consecutive patients with lower/middle rectal cancer who underwent surgery-first treatment were evaluated. The results of diagnostic examinations and the definitive pathological examination were considered and compared. Results: One hundred and one patients were enrolled in the study. The mean age was 72.5 (SD ± 9.7) years. F:M = 1:2. Mean distance from the anal orifice was 87 (SD ± 9.7) mm. Mean tumoral cranio-caudal extension was 35 (SD ± 12.5) mm. According to the T-stage, the κ coefficient showed a fair concordance between MRI and Pathology (κ = 0.294) and moderate between ERUS and Pathology (κ = 0.534). According to the N-stage, MRI was related to a lower concordance (κ = 0.138) than ERUS (κ = 0.337) with Pathology. Comparing ERUS with MRI, κ was higher in staging T (κ = 0.410), showing a moderate agreement. Stage N was related to a fair agreement between the two imaging methods (κ = 0.237). Conclusions: MRI and ERUS have similar results in performing the TN staging in patients with lower and middle rectal cancer who did not undergo neoadjuvant chemoradiotherapy. ERUS might be a valid option for staging patients who cannot have the possibility to perform an MRI.