Role of Preoperative Local and Distant Staging in Rectal Cancer

Abstract

Preoperative imaging in rectal cancer is very important, as accurate staging determines optimal treatment strategy. In this review, imaging modalities for locoregional and distant staging in rectal cancer are discussed. For local staging, superficial tumors are best staged using endorectal US (EUS), as EUS is the most accurate modality for assessment of tumor ingrowth into the rectal wall layers. The more advanced tumors are best imaged using MRI, because MRI accurately predicts the distance from tumor to mesorectal fascia, and thus the circumferential resection margin (CRM), as well as possible invasion into surrounding organs. For the prediction of the nodal status none of the three imaging modalities - EUS, MRI and CT - can be reliably used for clinical decisionmaking. Only MRI using lymph node specific contrast (such as ultrasmall paramagnetic iron oxide-enhanced MRI) seems promising for the detection of nodal disease. For the detection of distant metastases transabdominal ultrasound and chest X-ray are used as a primary screening tool. However, for the high prevalence group (stage III) both methods are insufficiently sensitive, and CT of the chest plus abdomen is preferred.

Preoperative Staging of Rectal Tumors: Comparison of Endorectal Ultrasound, Hydro-CT, and High-Resolution Endorectal MRI

“…Stage-adapted therapy of rectal cancer consists of TEM, TME, and abdominoperineal resection combined with pre-or postoperative radiochemotherapy [3][4][5]. The type of treatment depends on the extent of the tumor.…”

“…More recently, studies considering the circumferential resection margin (CRM), which is the shortest distance from the tumor to the mesorectal fascia, have been published. Various investigations indicated that the CRM correlates more precisely with the recurrence rate of rectal cancer than the T stage alone [3]. Surgical treatment options consist in transanal endoscopic microsurgery (TEM), anterior resection with total mesorectal excision (TME), or abdominoperineal resection [4].…”

Response to Preoperative Short-Course Radiotherapy in Locally Advanced Rectal Cancer: Value of ¹⁸F-Fluorodeoxyglucose Positron Emission Tomography

“…The two regimens of the BRCT form the population in the study described here. With the change of paradigm from adjuvant therapy to the increasing use of preoperative treatment in LARC, accurate staging and patient selection are crucial for appropriate therapy planning in order to avoid unnecessary treatment in early stage tumors [8]. The preoperative evaluation by endorectal ultrasound (EUS) and magnetic resonance imaging (MRI) is limited to morphologic information.…”

The Role of PET in Target Localization for Radiotherapy Treatment Planning

“…In two studies in rectal cancer, an increase in PET-based target volumes, when compared to CT-based ones, was observed [5,55]. However, PET in this location is used mainly for staging purposes [56]. In the thoracic region PET was found to be useful in the management of malignant pleural mesothelioma as well as to diagnose bleomycin-associated pneumonitis in seminoma treatment [57,58].…”