Work

Accuracy of Flexible Sigmoidoscopy and MRI in Restaging Rectal Cancer after Neoadjuvant Therapy

Year: 2025

Type: article

Abstract: OBJECTIVE: To measure the accuracy of flexible sigmoidoscopy (FS) and MRI in identifying a true response (TR) to total neoadjuvant therapy (TNT) in patients with locally advanced rectal cancer. BACKGROUND: Tumor response on restaging FS and MRI determines patient eligibility for watch-and-wait (WW). Prospective studies have not yet evaluated the accuracy of these testing modalities. METHODS: This was a secondary analysis of the OPRA trial. Patients underwent restaging assessment with FS and MRI 8±4 weeks after completing TNT. Those with a clinical complete (cCR) or near-complete (nCR) response were recommended for WW. Patients with an incomplete response were recommended for total mesorectal excision. A TR, defined as a sustained cCR for ≥2 years on WW or a pathologic complete response on surgical specimen, was the reference standard for the diagnostic performance analysis. RESULTS: Three hundred and four patients completed TNT; 265 (82%) had sufficient follow-up for inclusion in the diagnostic performance analysis. Fifty-two percent had a TR. Accuracy, sensitivity and specificity were 60%, 95% and 23% for MRI and 65%, 96% and 33% for FS. Combining FS and MRI improved accuracy to 67%. The combined modalities reliably predicted 5-year TME-free survival (log-rank P<0.001), with patients whose tumor response was classified as nCR by both assessments most likely to experience local regrowth. CONCLUSIONS: Endoscopic and radiologic assessment of rectal tumor response to neoadjuvant therapy is accurate in two-thirds of patients. FS is more likely than MRI to detect a TR and should take precedence when exams are discordant.

Source: Annals of Surgery

DOI: 10.1097/sla.0000000000006960