Ten-Year Outcomes of Patients with Rectal Cancer Remaining Lymph Node Positive After Preoperative Radiochemotherapy

Background: Persistent lymph node metastases after neoadjuvant radiochemotherapy (RCT) for locally advanced rectal cancer indicate poor response to treatment. This study evaluated the long-term prognosis of patients with residual nodal disease following neoadjuvant RCT and total mesorectal excision (TME) in comparison with patients who underwent upfront TME without adjuvant radiotherapy. Methods: Consecutive patients with rectal adenocarcinoma and histopathologically confirmed lymph node metastases after TME were identified from the prospectively maintained database of the colorectal unit at Dresden-Friedrichstadt General Hospital. Patients with distant metastases, in-hospital mortality, or postoperative radiotherapy were excluded. The two groups were comprehensively compared regarding patient-, tumor-, and treatment-related characteristics. Cumulative local recurrence, time to recurrence, cancer-specific survival, and overall survival were analyzed using the Kaplan-Meier method. Results: Between 1996 and 2021, 155 eligible patients were identified, including 101 patients in the RCT group and 54 in the upfront surgery group. Baseline characteristics were largely comparable, except for a higher median age (70.5 vs. 64 years, p < 0.001) and a higher proportion of lymphovascular invasion (36.0% vs. 15.2%, p = 0.004) in the upfront surgery group. Ten-year local recurrence rates were similar between groups (21.0% [95% CI: 10.4-31.6] vs. 20.8% [95% CI: 8.5-33.1], p = 0.609). No significant differences were observed in time to recurrence or cancer-specific survival. Overall survival was lower in the upfront surgery group, most likely reflecting the substantially higher age of these patients. Conclusions: Despite more intensive treatment, patients with a persistent ypN-positive category have outcomes no better than untreated patients with node-positive disease after TME, indicating a biologically high-risk subgroup. Non-response is therefore a sign of a negative selection. These patients may lose the opportunity for optimal local tumor control during prolonged neoadjuvant treatment, underscoring the urgent need for reliable predictive markers to identify non-responders and guide individualized treatment strategies.