Retrospective Cohort Study
Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Mar 21, 2015; 21(11): 3274-3281
Published online Mar 21, 2015. doi: 10.3748/wjg.v21.i11.3274
Ratio of metastatic lymph nodes is more important for rectal cancer patients treated with preoperative chemoradiotherapy
In Ja Park, Chang Sik Yu, Seok-Byung Lim, Yong Sik Yoon, Chan Wook Kim, Tae Won Kim, Jong Hoon Kim, Jin Cheon Kim
In Ja Park, Chang Sik Yu, Seok-Byung Lim, Yong Sik Yoon, Chan Wook Kim, Jin Cheon Kim, Department of colon and rectal Surgery, University of Ulsan College of Medicine and Asan Medical Center, Seoul 138-736, South Korea
Tae Won Kim, Department of Medical Oncology, University of Ulsan College of Medicine and Asan Medical Center, Seoul 138-736, South Korea
Jong Hoon Kim, Department of Radiation Oncology, University of Ulsan College of Medicine and Asan Medical Center, Seoul 138-736, South Korea
Author contributions: Park IJ designed study and write manuscript; Yu CS designed study and provided critical comments on manuscript; Lim SB, Yoon YS, Kim CW, Kim TW, Kim JH and Kim JC provided clinical data and were also involved in editing the manuscript; Kim JC provided critical comments on manuscript.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Chang Sik Yu, MD, PhD, Professor, Department of colon and rectal Surgery, University of Ulsan College of Medicine and Asan Medical Center, 86 Asanbyeongwon-gil, Songpa-gu, Seoul 138-736, South Korea. csyu@amc.seoul.kr
Telephone: +82-2-30103494 Fax: +82-2-4749027
Received: August 7, 2014
Peer-review started: August 8, 2014
First decision: August 27, 2014
Revised: October 6, 2014
Accepted: November 19, 2014
Article in press: November 19, 2014
Published online: March 21, 2015
Abstract

AIM: To evaluate the predictive value of the lymph node (LN) ratio (LNR, number of metastatic LNs/ examined LNs) for recurrence in patients with rectal cancer and to compare its applicability according to preoperative chemoradiotherapy (PCRT).

METHODS: From 2000 to 2009, 967 patients with metastatic LNs after curative resection for locally advanced rectal cancer were identified. Patients were categorized according to PCRT (PCRT vs No PCRT). The cut-off LNR was determined based on the pN1 vs pN2 when the recommended number of LNs was harvested. The 5-year recurrence-free survival (RFS) rates using the Kaplan-Meier method were compared according to p/yp N stage and the LNR in each group.

RESULTS: Among patients with the same p/ypN stage, the 5-year RFS rate differed according to the LNR. In addition, the 5-year RFS rate was significantly different between pN and LNR groups in patients with No PCRT. In PCRT group, however, only LNR was associated with prognosis. On multivariate analysis, both pN and LNR were significant independent prognostic factors for 5-year RFS in the No PCRT group. In the PCRT group, only LNR category was found to be associated with RFS (HR = 2.36, 95%CI: 1.31-3.84, and P = 0.001).

CONCLUSION: The LNR is an important prognostic predictor of RFS in rectal cancer patients especially treated with PCRT. Current pN categories could not discriminate between prognostic groups of RFS after PCRT.

Keywords: Rectal cancer, Preoperative chemoradiotherapy, Lymph node ratio, Prognosis, pN

Core tip: The number of metastatic lymph node might show different prognosis according to the number of examined lymph node. Retrieved number of lymph node after preoperative chemoradiotherapy (PCRT) has been known fewer than those without PCRT. However, number of metastatic lymph nodes used in pathologic staging was same between patients treated with PCRT and those without PCRT. The present study suggests the metastatic lymph node ratio would be useful prognostic indicator and it is more prominent in patients treated with PCRT.