Can Ultrasound Elastography Discriminate between Rectal Adenoma and Cancer? A Systematic Review

Simple Summary It is important to obtain correct preoperative classification of rectal polyps and cancer prior to making treatment decisions but distinguishing between the two can be challenging. International societies recommend magnetic resonance imaging and endorectal ultrasound as part of the initial preoperative evaluation. The ultrasound examination can be improved by applying a tissue stiffness measurement, known as elastography. Our aim was to investigate the performance of elastography in the staging of rectal tumors. We systematically searched the literature and found six eligible studies. They all reported increased accuracy by elastography compared with ultrasound examination alone. Background: Rectal cancer is a common malignancy. Since the introduction of bowel-screening programs, the number of patients with advanced adenomas and early rectal cancer has increased. Despite improved diagnostics, the discrimination between rectal adenomas and early rectal cancer (i.e., pT1-T2) remains challenging. The purpose of this systematic review was to evaluate the diagnostic performance of endorectal ultrasound (ERUS) elastography in discriminating rectal adenomas from cancer. Method: Using PRISMA guidelines, a systematic search was performed on PubMed, Embase, and MEDLINE databases. Studies evaluating the primary staging of rectal adenomas and cancer using ERUS elastography were included. Results: Six studies were identified; three evaluated the discrimination between adenomas and cancer; two evaluated adenomas and early rectal cancer (i.e., pT1-T2); one evaluated performance on different T categories. All studies reported increased diagnostic accuracy of ERUS elastography compared to ERUS. Sensitivity, specificity and accuracy ranged 0.93-1.00, 0.83-1.00 and 0.91-1.00, respectively, when discriminating adenomas from cancer. In the differentiation between adenomas and early rectal cancer, the sensitivity, specificity and accuracy were 0.82-1.00, 0.86-1.00 and 0.84-1.00, respectively. Conclusion: Elastography increases the accuracy of ERUS and may provide valuable information on malignant transformation of rectal lesions.

Automated summary

Accurate preoperative classification of rectal polyps and cancer is crucial, with magnetic resonance imaging and endorectal ultrasound recommended for initial evaluation. Elastography can improve ultrasound accuracy, as shown in six eligible studies, all reporting increased diagnostic accuracy with elastography compared to ultrasound alone. Despite improved diagnostics, discrimination between rectal adenomas and early cancer remains challenging, highlighting the potential of elastography in aiding the differentiation.