Challenging the Feasibility and Clinical Significance of Current Guidelines on Lymph Node Examination in Rectal Cancer in the Era of Neoadjuvant Therapy

Abstract

PurposeWe sought to examine the feasibility and clinical significance of current guidelines on nodal assessment in patients with rectal cancer (RC) treated with neoadjuvant radiation.MethodsAll patients with RC treated with curative surgery from 1991 to 2003 were included. Number of lymph nodes (LNs) assessed was compared between patients who received neoadjuvant therapy and surgery (NEO) and patients who underwent surgery alone (SURG). Impact of node retrieval on node positivity and disease-specific survival (DSS) in NEO patients was assessed.ResultsIn total, 708 patients were identified, of whom 429 (61%) were in the NEO group. These patients had significantly fewer nodes assessed than SURG patients (unadjusted mean, 10.8 v 15.5; adjusted mean difference, −5.0 nodes; P < .001). In the NEO group, 63% of patients had fewer than 12 nodes retrieved (P < .001 v SURG). The proportion of patients diagnosed with node-positive disease in the NEO group was significantly and monotonically associated with the number of lymph nodes retrieved, with no plateau in the relationship. Fewer nodes retrieved was not associated with inferior DSS.ConclusionIn a tertiary cancer center, the 12-LN threshold was not relevant and often not achievable in patients with RC treated with neoadjuvant therapy. Lower LN count after neoadjuvant treatment was not associated with understaging or inferior survival. Although we support the critical importance of careful pathologic examination and adequate nodal staging, we challenge the relevance of LN count both in clinical practice and as a quality indicator in RC.