Prognostic Impact of Extranodal Extension in Rectal Cancer Patients Undergoing Radical Resection After Preoperative Chemoradiotherapy

Extranodal extension (ENE) in rectal cancer after preoperative chemoradiotherapy (PCRT) has not been extensively investigated. This study assessed ENE and its prognostic impact in rectal cancer after PCRT. ENE was closely related to advanced tumor stage and poor survival outcome. Background: Extranodal extension (ENE) of nodal metastasis has emerged as an important prognostic factor in many malignancies, including rectal cancer. However, its significance in patients with rectal cancer receiving preoperative chemoradiotherapy (PCRT) has not been extensively investigated. We therefore assessed ENE and its prognostic impact in a large series of consecutive rectal cancer patients with lymph node metastasis after PCRT and curative resection. Patients and Methods: Between January 2000 and December 2014, a total of 1925 patients with rectal cancer underwent surgical resection after PCRT. Medical records of 469 patients with pathologic node positivity were retrospectively reviewed. Results: Of the 469 patients, 118 (25.2%) presented with ENE. ENE was observed more frequently in those with advanced tumor stage (higher ypT, ypN, and ypStage), lymphovascular invasion, and perineural invasion. Five-year disease-free survival rate was lower in patients with ENE-positive tumors than those with ENE-negative tumors (36.1% vs. 52.3%, P = .003). Similarly, 5-year overall survival rate was lower in patients with ENE-positive tumors than those with ENE-negative tumors (60.2% vs. 70.6%, P < .001). Multivariate analysis revealed that the presence of ENE was an independent poor prognostic factor for disease-free survival (hazard ratio = 1.412; 95% confidence interval, 1.074-1.857; P = .013) and overall survival (hazard ratio = 1.531; 95% confidence interval 1.149-2.039; P = .004). Conclusion: The presence of ENE in patients with rectal cancer undergoing PCRT is a negative prognostic factor, reflecting poor survival outcome.