Endorectal Ultrasound: Its Role in the Diagnosis and Treatment of Rectal Cancer

Abstract

With development over the past 25 years of new surgical techniques and neoadjuvant therapy regimens for rectal cancer, physicians now have a range of treatment options that minimize morbidity and maximize the potential for cure. Accurate pretreatment staging is critical, ensuring adequate therapy and preventing overtreatment. Many options exist for staging primary rectal cancer. However, endorectal ultrasound (ERUS) remains the most attractive modality. It is an extension of the physical examination, and can be performed easily in the office. It is cost effective and is generally well tolerated by the patient, without need for general anesthesia. The authors discuss the data currently available on ERUS, including its accuracy and limitations, as well as the technical aspects of performing ERUS and interpreting the results. They also discuss new ultrasound technologies, which may improve rectal cancer staging in the future. KEYWORDS: Endorectal ultrasound, rectal cancer, evaluation, stagingObjectives: On completion of this article, the reader should be able to understand the current role, the potential roles, and the limitations of endorectal ultrasound in the evaluation of rectal cancer.Rectal cancer remains a significant health concern worldwide, affecting over 40,000 people annually 1 in the United States alone. Recurrence rates approach 50% in the setting of stage II and III disease.2 The narrow confines of the bony pelvis make surgical extirpation challenging. Incomplete resection leads to local recurrence, 3 which is associated with high morbidity. Postoperative chemoradiation has been shown to reduce the rate of local relapse from 25% to 16%, prompting the National Institutes of Health (NIH; Bethesda, MD) to issue a consensus statement advocating adjuvant therapy for all stage II and III rectal cancer patients.4-6 A recent prospective, randomized trial by the German Rectal Cancer Study Group demonstrated that preoperative chemoradiation results in even lower rates of local recurrence, reduced treatment toxicity, and improved rates of sphincter preservation.7 Indeed, many series reporting on combined modality therapy (CMT)-preoperative chemoradiation followed by total mesorectal excision-demonstrate local recurrence rates of less than 10% 8 in the setting of locally advanced lesions. These studies highlight the need for proper staging prior to initiation of treatment. 9Endorectal ultrasound is currently the most widely used and effective diagnostic modality in the assessment of rectal cancer overall. Its accuracy in numerous trials and meta-analyses ranges from 80 to 95% for T-staging and 70 to 75% for N-staging, levels that

Endorectal Ultrasound-Guided Fine-Needle Aspiration: A Useful Diagnostic Tool for Perirectal and Intraluminal Lesions

“…Restaging after neoadjuvant chemoradiation therapy is compromised by the effects of chemoradiation such as inflammation, edema, necrosis, and fibrosis. Postradiation changes such as fibrosis are difficult to distinguish from the residual tumor, and thus poor staging results mainly from overstaging [1,33]. ERUS-FNA allows cytologic examination of any suspicious lymph node or intramural mass.…”

“…It can be used to confirm malignancy in suspicious lesions as well as to identify and confirm nodal metastasis, tumor recurrence, or metastatic spread. Assessment of the depth of tumor penetration provides information for T staging in the TNM classification, and the ultrasonographic staging is suggested by the prefix ‘u’ [1]. For N staging, involvement is usually suspected if a lymph node is over 5 mm in diameter, round, and hypoechoic, features which may differentiate it from inflammatory nodes [2].…”

Limits of Endorectal Ultrasound in Tailoring Treatment of Patients with Rectal Cancer

“…Data from previous reviews and meta-analysis have shown similar rates of lymph node staging accuracy ranging from 60 to 74%, while the mean overall T correspondence was reported to be higher, that is, around 85% [4,12,13,14,15]. Our results suggest that the diagnostic yield of ERUS might have been overestimated.…”

The Role of Endorectal Ultrasound and Magnetic Resonance Imaging in the Management of Early Rectal Lesions in a Tertiary Center

“…This might have contributed to the overstaging, although we have not been able to fully assess this. [25][26][27] Puli et al performed a meta-analysis of 42 studies comprised of 5039 patients conducted between 1986 and 2008. 28 Their primary outcome was assessment of T-stage, where they demonstrated a pooled sensitivity of > 80% and a pooled specificity of > 90% for all T-stages.…”