Originally published as JCO Early Release 10.1200/JCO.2007.12.7704 on March 24 2008

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Prognostic Implications of the Distribution of Lymph Node Metastases in Rectal Cancer After Neoadjuvant Chemoradiotherapy

Tobias Leibold, Jinru Shia, Leyo Ruo, Bruce D. Minsky, Timothy Akhurst, Marc J. Gollub, Michelle S. Ginsberg, Steven Larson, Elyn Riedel, W. Douglas Wong, José G. Guillem

From the Departments of Surgery, Pathology, Radiation Oncology, Nuclear Medicine, Radiology, and Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center, New York, NY

Corresponding author: José G. Guillem, MD, MPH, Colorectal Service, Memorial Sloan-Kettering Cancer Center, 1275 York Ave, Room C-1077, New York, NY 10021; e-mail: guillemj{at}mskcc.org

Purpose: After preoperative chemoradiotherapy of rectal cancer, the number of retrievable and metastatic lymph nodes is decreased. The current TNM classification is based on number and not location of lymph node metastases and may understage disease after chemoradiotherapy. The aim of this study was to examine the prognostic significance of location of involved lymph nodes in rectal cancer patients after preoperative chemoradiotherapy.

Patients and Methods: We prospectively examined whole-mount specimens from 121 patients with uT3-4 and/or N+ rectal cancer who received preoperative chemoradiotherapy followed by resection. Location of involved lymph nodes was compared with median number of lymph nodes involved as well as presence of distant metastasis at presentation.

Results: Lymph node metastases were detected in 37 patients (31%). Thirteen patients with lymph node involvement along major supplying vessels (proximal lymph node metastases) had a significantly higher rate of distant metastatic disease at time of surgery than patients without proximal lymph node involvement (P < .001); median number of lymph nodes involved was two for patients with proximal lymph node metastases and 1.5 for patients with mesorectal lymph node involvement alone.

Conclusion: Our data suggest that, after preoperative chemoradiotherapy, proximal lymph node involvement is associated with a high incidence of metastatic disease at time of surgery. Because the median number of involved lymph nodes is low after preoperative chemoradiotherapy, the TNM staging system may not provide an accurate assessment of metastatic disease. Therefore, the ypTNM staging system should incorporate distribution as well as number of lymph node metastases after preoperative chemoradiotherapy for rectal cancer.

published online ahead of print at www.jco.org on March 24, 2008.

Supported in part by National Cancer Institute Grant No. R01 82534-01 (J.G.G).

Authors’ disclosures of potential conflicts of interest and author contributions are found at the end of this article.