Transanal Endoscopic Microsurgery for Residual Rectal Cancer (ypT0-2) Following Neoadjuvant Chemoradiation Therapy: Another Word of Caution

BACKGROUND: Significant tumor downstaging among patients with rectal cancer following neoadjuvant chemoradiation has raised the issue of offering patients with small residual cancers restricted to the bowel wall an alternative treatment strategy to total mesorectal excision. Transanal endoscopic microsurgery may allow proper primary tumor resection with promising oncological outcomes, less postoperative morbidity, and minimal long-term sexual, urinary, and fecal continence disorders in comparison with radical resection. OBJECTIVE: The aim of this study was to determine the oncological outcomes of patients with residual rectal cancers restricted to the rectal wall (ypT0-2) following neoadjuvant chemoradiation and transanal endoscopic microsurgery. DESIGN: This study considered a prospective cohort of patients with residual rectal cancers following neoadjuvant chemoradiation treated by transanal endoscopic microsurgery and no additional systemic therapy. SETTINGS: This study was a single-institution experience. PATIENTS: Patients with adenocarcinoma of the rectum located no more than 7 cm from the anal verge and endorectal ultrasound-or magnetic resonance-staged cT2-4N0-2M0 treated by neoadjuvant chemoradiation (50.4-54 Gy and 5-fluorouracil-based chemotherapy) were eligible for the study. Patients with small residual tumors (<= 3 cm) radiologically staged ycT0-2N0 were treated by transanal endoscopic microsurgery. INTERVENTIONS: Transanal endoscopic microsurgery was performed. MAIN OUTCOME MEASURES: The primary outcome measured was local recurrence. RESULTS: Of the 27 patients treated by transanal endoscopic microsurgery, 3 had ypT0, 6 had ypT1, and 18 had ypT2 cancers. All patients underwent R0 transanal endoscopic microsurgery excision. Local recurrence was observed in 4 (15%) patients after a median follow-up of 15 months. Only lymphovascular invasion was an independent predictive factor for local failure (p = 0.04). Tumor size, ypT status, T-status downstaging, lateral/radial margins, and tumor regression grade were not predictors of local failure. LIMITATIONS: This study was limited by the small sample size and limited follow-up. CONCLUSIONS: A local failure rate of 15% after transanal endoscopic microsurgery for patients with residual rectal cancers restricted to the bowel wall (ypT0-2) may limit the indication of this procedure to highly selected patients as an alternative to standard radical total mesorectal excision.