Endoscopic Ultrasound in Pancreatic Cancer

Abstract

Accurate staging of rectal cancer is essential for selecting patients who may undergo local endoscopic or surgical procedures or sphincter-preserving surgery and for identifying those who might benefit from neoadjuvant therapy. Performing transrectal endoscopic ultrasound (EUS) is strongly recommended (power of evidence 2b, strong consensus) in the current S3-Guideline (2008) for staging of rectal cancer. Whereas usually EUS is done with rigid instruments, we prefere to use flexible echoendoscopes that are able to traverse a stenotic tumor and perform fine needle aspiration (FNA). EUS is superior for T staging of rectal cancer (in comparison to CT and MRI), in several studies diagnostic accuracy is reported in 80-95%, in daily practice 85% can be achieved provided an experienced endosonographer is available. Nodal involvement in rectal cancer (N stage) can not be sufficiently diagnosed by any imaging modality; the accuracy of EUS has been suggested in 70-75% (in a large study 65%), the main reason for not visualizing all metastatic lymph nodes is that 45% of them are smaller than 5 mm in size. In early T stages with suspected nodal disease FNA is useful. The extent of tumor involvement of the mesorectal fascia defining the circumferential resection margin, which has important prognostic implications, cannot be sufficiently estimated by EUS, it should be diagnosed using MRI. EUS plays a very important role in early detection of recurrent rectal cancer which often develops extraluminally. Despite the difficulties in differentiating postoperative or post-radiation changes FNA can prove tumor recurrence. Even though there is no general agreement we think that patients with a locally advanced tumor or a local excision should undergo an aggressive surveillance including EUS.