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World J Gastroenterol. Feb 14, 2010; 16(6): 691-697
Published online Feb 14, 2010. doi: 10.3748/wjg.v16.i6.691
How useful is rectal endosonography in the staging of rectal cancer?
Taylan Kav, Yusuf Bayraktar
Taylan Kav, Yusuf Bayraktar, Division of Gastroenterology, Department of Medicine, Hacettepe University School of Medicine, Sihhiye, Ankara 06100, Turkey
Author contributions: Kav T and Bayraktar Y contributed equally to this work.
Correspondence to: Taylan Kav, MD, Division of Gastroenterology, Department of Medicine, Hacettepe University School of Medicine, Sihhiye, Ankara 06100, Turkey.
Telephone: +90-312-3051712 Fax: +90-312-4429429
Received: September 2, 2009
Revised: October 12, 2009
Accepted: October 19, 2009
Published online: February 14, 2010

It is essential in treating rectal cancer to have adequate preoperative imaging, as accurate staging can influence the management strategy, type of resection, and candidacy for neoadjuvant therapy. In the last twenty years, endorectal ultrasound (ERUS) has become the primary method for locoregional staging of rectal cancer. ERUS is the most accurate modality for assessing local depth of invasion of rectal carcinoma into the rectal wall layers (T stage). Lower accuracy for T2 tumors is commonly reported, which could lead to sonographic overstaging of T3 tumors following preoperative therapy. Unfortunately, ERUS is not as good for predicting nodal metastases as it is for tumor depth, which could be related to the unclear definition of nodal metastases. The use of multiple criteria might improve accuracy. Failure to evaluate nodal status could lead to inadequate surgical resection. ERUS can accurately distinguish early cancers from advanced ones, with a high detection rate of residual carcinoma in the rectal wall. ERUS is also useful for detection of local recurrence at the anastomosis site, which might require fine-needle aspiration of the tissue. Overstaging is more frequent than understaging, mostly due to inflammatory changes. Limitations of ERUS are operator and experience dependency, limited tolerance of patients, and limited range of depth of the transducer. The ERUS technique requires a learning curve for orientation and identification of images and planes. With sufficient time and effort, quality and accuracy of the ERUS procedure could be improved.

Keywords: Rectal cancer, Colorectal cancer, Staging, Endorectal ultrasonography, Endorectal ultrasound, Accuracy, Tumor invasion, Nodal metastases, Other rectal tumors, Diagnostics