Anorectal staging: is EUS necessary?

A correct preoperative staging of rectal cancer is important because overall survival and disease-free survival are dependent on TN stage and treatment method. Initially endorectal ultrasound (ERUS) was the mainstay in many institutions for the local staging of all rectal carcinomas. It was more accurate than CT and magnetic resonance imaging (MRI) for the evaluation of local invasion and had a comparable diagnostic accuracy for lymph node involvement. In recent years there has been a shift away from ERUS for the staging of rectal cancer. This can be partially explained by factors linked to ERUS such as the low reported accuracy in the staging of rectal cancer in some recent studies and the operator dependency. A more important reason for the shift is caused by improvements in MRI technology. MRI has taken over the role of ERUS in a lot of centers because it is better tolerated, can be used in stenotic tumors and it can assess the circumferential resection margin. This extramural spread is the most important prognostic indicator with regard to T stage and tilts the balance towards MRI as the modality of choice for advanced rectal cancers. ERUS is still important in the pre-operative staging of early rectal cancer and can help in selecting patients eligible for local excision. ERUS can also have an added value to improve N staging by performing FNA.