Management of Responsive Lateral Pelvic Nodes After Neoadjuvant Therapy in Rectal Cancer (RESPONDER)

To determine whether lateral pelvic lymph node dissection improves oncological outcomes in patients with rectal cancer with radiologically responsive lateral pelvic nodes (LPNs) following neoadjuvant chemoradiotherapy (nCRT).

The optimal management of radiologically responsive LPNs after nCRT remains unclear.

This retrospective cohort study included patients with mid-to-low rectal adenocarcinoma who underwent radical resection between 2012 and 2022 at eight tertiary centers. Eligible patients had baseline magnetic resonance imaging evidence of lateral pelvic node enlargement (short-axis ≥5 mm) that decreased to <5 mm after nCRT. Inverse probability of treatment weighting was used to address selection bias. Weighted Kaplan-Meier and Cox proportional hazards models were used to compare disease-free survival, overall survival, and local recurrence.

Of 844 patients, 451 underwent total mesorectal excision alone and 393 underwent total mesorectal excision with LPN dissection. Dissection was associated with longer operative time (279.3 vs. 237.9 min; P <0.001) and higher early complication rates (27.0% vs. 19.6%; P =0.011). The 5-year local recurrence, disease-free survival, and overall survival rates were 3.1% vs. 5.3% (hazard ratio [HR], 0.738; 95% confidence interval [CI], 0.207-2.634; P =0.640), 77.1% vs. 71.4% (HR, 0.80; 95% CI, 0.50-1.29), and 87.0% vs. 86.9% (HR, 0.79; 95% CI, 0.22-2.81) with and without lymph node dissection, respectively.

Among patients with radiologically responsive LPNs after nCRT, omission of lateral pelvic lymph node dissection did not compromise oncological outcomes. These data support a response-based surgical strategy to reduce operative morbidity without affecting recurrence or survival rates.