Staging Anal Cancer: Prospective Comparison of Transanal Endoscopic Ultrasound and Magnetic Resonance Imaging

The staging of anal cancer is extremely important for therapy and prognosis. Transanal endoscopic ultrasound and magnetic resonance imaging are routinely applied. The aim of this prospective comparative study is to evaluate whether tumor staging is concordant between these techniques. Forty-five anal cancer patients underwent endoscopic ultrasound and magnetic resonance imaging. Histological confirmation was obtained in all patients. The two test methods were compared with the kappa concordance index and sensitivity for the initial method of tumor detection was calculated. For six patients who were operated upon because of tumor progression, the results were evaluated against the histological tumor stage. High concordance was found in the assessment of tumor size and nodal status (kappa index 0.63 and 0.77). Cancer patients were correctly identified with 100% sensitivity (45/45) by endoscopic ultrasound and with 88.9% (40/45) sensitivity by magnetic resonance imaging. In the six operated patients, T stage was correctly assessed in four of six patients by endoscopic ultrasound and in three of six patients by magnetic resonance imaging. The results of endoscopic ultrasound strongly coincide with those of magnetic resonance imaging. Endoscopic ultrasound may be superior to magnetic resonance imaging for detection of small superficial tumors. However, magnetic resonance imaging is needed for N staging.