Optimal Methods for Staging Rectal Cancer

Abstract

At present, several modalities exist for the preoperative staging of rectal lesions, including computed tomography (CT), body coil or endorectal coil magnetic resonance imaging (MRI), endoscopic ultrasonography (EUS) done by rigid or flexible probes, and positron emission tomography (PET). Staging accuracy for CT ranges from 53% to 94% for T-stage accuracy and from 54% to 70% for N-stage accuracy. Improved CT accuracy is observed at higher disease stages. Body coil MRI has shownT-and N-stage accuracy ranging from 59% to 95% and 39% to 95 %, respectively. Endorectal coil MRI has shown improved T-and N-stage accuracy, with rates of 66% to 91% and 72% to 79%, respectively. The development of phased-array MRI, combining high spatial resolution with a larger field of view, offers promise to improve on these rates. EUS, considered the current gold standard, has shown T-stage accuracy ranging from 75% to 95%, with N-stage accuracy ranging from 65% to 80%. Flexible EUS probes have the advantage of being able to access and sample iliac nodes. Recent studies also suggest that three-dimensional EUS may provide greater accuracy than conventional two-dimensional EUS. Limited studies exist on the use of PET in primary tumor staging. PET may upstage disease in 8% to 24% of patients and has also been used in posttreatment restaging and surveillance. Postradiation edema, necrosis, and fibrosis seem to decrease restaging accuracy in all modalities. This article reviews the current literature about the staging accuracy of the various modalities and suggests a staging algorithm for rectal cancer.Accurate staging of rectal cancer is necessary to provide the optimal treatment strategy. Staging information includes extent of tumor involvement of the rectal wall and adjacent structures, presence or absence of adjacent lymphadenopathy, and determination of distant metastasis. Preoperative radiation therapy and total mesorectal excision (TME) are increasingly used in the treatment of locally advanced rectal cancer to reduce tumor recurrence. Recent data have shown that preoperative radiation therapy can reduce tumor recurrence from 27% to 11% (1). In addition, TME (a surgical technique that removes the rectum and surrounding mesorectal fat and perirectal lymph nodes and surrounding mesorectal fascia) has been shown to reduce postoperative recurrence to 10% without radiation therapy (2). A recent randomized controlled trial has shown that the combination of these techniques may reduce recurrence to 2.4% at 2 years compared with 8.2% with TME alone (3). Thus, accurate local staging information is paramount for stratifying patients who would benefit from neoadjuvant therapy as well as for predicting the surgical approach. Figure 1 illustrates major decision points that should be addressed in the staging process.At present, several modalities exist for the preoperative staging of rectal cancer: computed tomography (CT); magnetic resonance imaging (MRI) with traditional body, endorectal, or phased-array coils; endorectal ultrasonogra...

Surgical treatment for rectal cancer: An international perspective on what the medical gastroenterologist needs to know

“…TRUS is most accurate for early rectal cancers in the distal half of the rectum, and is particularly valuable in assessing the T-stage. The limited penetration depth of 7 MHz ultrasound waves makes it difficult to access the N-stage with high precision, with most studies showing accuracy of 70%-75% [5] . Three dimensional rectal ultrasound imaging seems to improve the staging properties [5] .…”

“…The limited penetration depth of 7 MHz ultrasound waves makes it difficult to access the N-stage with high precision, with most studies showing accuracy of 70%-75% [5] . Three dimensional rectal ultrasound imaging seems to improve the staging properties [5] . Thus, for making a decision about whether local resection is possible the results of TRUS are of significant importance.…”

“…Because standard protocols can be used, and because it is less operator dependent, MRI has become the standard for preoperative stage assessment of rectal tumors [5] . With its high resolution and accuracy MRI can give information about T-stage and N-stage as well as distance to planned resection margins, especially lateral or circumferential margins within the pelvic cavity.…”

3D echoendoscopy and miniprobes for rectal cancer staging

“…Magnetic resonance imaging, endoluminal ultrasound and computed tomography are imaging tools commonly used to evaluate rectal tumor staging (1). Rectal endoluminal ultrasonography (US) with rigid probes or endoscopic ultrasonography (EUS) is the preferential method for local staging of rectal carcinoma (RC) and decisively influences the therapeutic approach of patients (2).…”

“…Rectal endoluminal ultrasonography (US) with rigid probes or endoscopic ultrasonography (EUS) is the preferential method for local staging of rectal carcinoma (RC) and decisively influences the therapeutic approach of patients (2). Nevertheless, its accuracy varies significantly, ranging from 63% to 95% for T staging and from 64% to 80% for N staging (1,(3)(4)(5). It is well known that operator expertise is an important factor in the accuracy of RC by endoluminal US (6).…”