Correlation between endorectal ultrasonography, magnetic resonance imaging and final histological examination in patients undergoing surgery for rectal cancer: a monocentric study on the first 50 cases.

Background: Endorectal ultrasound (ERUS) and magnetic resonance imaging (MRI) are key diagnostic tools for rectal cancer staging. ERUS is preferred for early-stage cancer, while MRI is the standard for advanced stages. However, their effectiveness in patients undergoing neoadjuvant therapy (NAT) remains debated. This study compares ERUS and MRI in rectal cancer evaluation, correlating results with final histopathological findings and analyzing a subgroup of patients who received NAT.

Methods: A retrospective study (February 2020 to February 2024) included oncology patients with rectal cancer treated electively at our Center, who had undergone both ERUS and MRI staging.

Results: Out of 172 surgical patients, 50 met inclusion criteria (42% male, average age 71.9). Surgical procedures included 36 anterior rectal resections and 14 abdominoperineal resections, with a laparoscopic approach in 84% of cases. Additionally, 74% underwent NAT. ERUS showed high sensitivity and specificity for early-stage (T1 and T2) and lymph node detection, while MRI was optimal for T3 and T4 staging. Correlation with histological findings was strong for ERUS and less so for MRI. In NAT patients, results were consistent, but MRI showed better accuracy for lymph node involvement.

Conclusions: ERUS and MRI are essential for rectal cancer diagnostics. ERUS is superior for early stages and lymph node evaluation, whereas MRI excels in advanced stages (T3 and T4). In NAT patients, ERUS remains favourable, but MRI's sensitivity and specificity improve for lymph node assessment.