Abstract
Accurate staging for low rectal cancer is essential for selecting patients who can undergo sphincter-preserving surgery and identifying those who could benefit from neoadjuvant therapy. In this article we review the literature and report our experience in preoperative locoregional staging of low rectal cancer with ultrasonographic methods. Nearly 30 years after its introduction into clinical practice Endorectal Ultrasound (ERUS) is established as a main diagnostic modality for locoregional staging of colorectal cancer. The accuracy of the method for assessing the tumor invasion (T-stage) varies between 80% to 95%. Endorectal ultrasound is the preferred method for rectal cancer staging in early T1 and T2 lesions. This method is less precise in evaluating lymph nodes (N-stage). A median accuracy of 75% is reported. With endoultrasound – guided fine needle aspiration biopsy the specificity and sensitivity of ERUS for confirming the malignant character of lymph nodes and local recurrence are improved. Three dimensional ERUS has some benefits in comparison to its 2D counterpart. The method allows better estimation of the volume of the tumor and the relation to nearby anatomical structures. In low rectal and anal carcinoma, ERUS and transperineal ultrasound can be used to evaluate the intactness of anal sphincter apparatus. Transvaginal ultrasound can be done as an addition to every ERUS examination in women with rectal cancer. This approach is very useful in cases of rectal stenotic tumors.
Highlights
Rectal cancer comprises approximately one third of all colorectal carcinomas, and of these approximately a third arise < 6 cm from the anal verge
In rectal carcinoma about 50% of metastatic lymph nodes are smaller than 5 mm; up to 8% can be smaller than 2 mm or even smaller [10,12,15]
When endorectal examination is performed with convex, but no radial probe, a rotation of the Transvaginal ultrasound can be done as an addition to every Endorectal Ultrasound (ERUS) examination in women with rectal cancer
Summary
Rectal cancer comprises approximately one third of all colorectal carcinomas, and of these approximately a third arise < 6 cm from the anal verge. By endorectal ultrasonography the rectal tumors can be evaluated for their size, stage, echostructure and vascularization. Ultrasound Methods for Lower Rectal Cancer Staging process) are examined.
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