Should Endoscopic Ultrasound (EUS) Be a Mandatory Component of the Pre Treatment Staging of All Newly Diagnosed Rectal Cancers? A Prospective Study

Abstract

Background and Aims: Accurate pre treatment staging of rectal cancer is critical to determine the need for induction therapy. EUS has been advocated as important in staging rectal cancer. This prospective blinded study analyzes the clinical impact of EUS as an adjunct to digital rectal exam (DRE), endoscopic appearance of the tumor, and CT for staging rectal cancer. Materials and Methods: Patients diagnosed with rectal cancer underwent DRE, sigmoidoscopy, CT, and EUS. One of 2 colorectal surgeons (CMF or EFF) performed a DRE, endoscopically viewed the tumor, and reviewed CT scans. They were then asked to make a management decision recommending primary resection, induction therapy followed by resection, or palliation. DRE and EUS were performed by 1 ultrasonographer (VMS) blinded to staging established by the surgeon's clinical evaluation. The EUS staging was made available to the surgeons. The pre EUS and post EUS treatment plans were compared to assess the impact on treatment decisions. Coefficients of agreement (K) were calculated between the staging results. Results: 60 patients (mean age of 59) were enrolled. In 5 cases, the lesions could not be fully palpated. There was excellent correlation between the DRE of the gastroenterologist and surgeons (K = 0.83, 95% CI 0.57-0.99) as well as between the surgeons' clinical staging and EUS staging (K = 0.70, 95% CI 0.50-0.91). EUS changed staging in 6 cases: 2 were upstaged from T2 to T3, 3 were downstaged from T3 to T2, and 1 was restaged from T3 to T2N1. The surgeons altered their treatment strategy for 3 of 6 patients based on EUS staging results. In 3 cases, despite the change of EUS staging, the surgeons maintained their original treatment strategy: 1 was restaged from T3 to T2N1 and was offered induction therapy. The second was downstaged by EUS but still offered neoadjuvant therapy for sphincter salvage. The third was upstaged from T2 to T3 by EUS, however the surgeon decided on induction regardless secondary to a prior history of rectal cancer. The addition of the EUS to the other clinical evaluations altered management in 3 of 60 cases (5%). Conclusion: The addition of rectal EUS to endoscopic evaluation, CT scan, and DRE performed by experienced colorectal surgeons rarely alters clinical decisions in the treatment of newly diagnosed rectal cancer. This seems especially true with cancers at the extremes of pathologic involvement. However, when the tumor is too proximal to feel by DRE, or in those tumors on the border between T2 and T3, EUS may be a valuable adjuvant for pretreatment clinical staging. EUS should be used selectively in the initial evaluation of rectal cancer.