Retrospective Cohort Study
Copyright ©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Clin Cases. Dec 26, 2020; 8(24): 6229-6242
Published online Dec 26, 2020. doi: 10.12998/wjcc.v8.i24.6229
Impact factors of lymph node retrieval on survival in locally advanced rectal cancer with neoadjuvant therapy
Shi-Wen Mei, Zheng Liu, Zheng Wang, Wei Pei, Fang-Ze Wei, Jia-Nan Chen, Zhi-Jie Wang, Hai-Yu Shen, Juan Li, Fu-Qiang Zhao, Xi-Shan Wang, Qian Liu
Shi-Wen Mei, Zheng Liu, Zheng Wang, Wei Pei, Fang-Ze Wei, Jia-Nan Chen, Zhi-Jie Wang, Hai-Yu Shen, Juan Li, Fu-Qiang Zhao, Xi-Shan Wang, Qian Liu, Department of Colorectal Surgery, National Cancer Center/National Clinical Research Center for Cancer/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China
Author contributions: Mei SW, Chen JN and Wang ZJ designed the research; Wei FZ, Shen HY, Li J and Zhao FQ collected the data; Pei W, Wang Z, Liu Z and Wei FZ analyzed the data; Mei SW drafted the manuscript; Liu Q and Wang XS revised the paper.
Supported by National Key Research and Development Plan "Research on Prevention and Control of Major Chronic Non-Communicable Diseases", No. 2019YFC1315705; and The Medicine and Health Technology Innovation Project of Chinese Academy of Medical Sciences, No. 2017-12M-1-006.
Institutional review board statement: The study received approval from the ethics committee of the National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College (Approval No. 17-116/1439).
Informed consent statement: All study participants, or their legal guardian, provided informed written consent prior to study enrollment.
Conflict-of-interest statement: The authors declare there is no conflict of interest in regard to this research.
Data sharing statement: No additional data are available.
STROBE statement: The authors have read the STROBE Statement-checklist of items, and the manuscript was prepared and revised according to the STROBE Statement-checklist of items.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (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/
Corresponding author: Qian Liu, MD, Chief Doctor, Department of Colorectal Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 17 Panjiayuan Nanli, Chaoyang District, Beijing 100021, China. fcwpumch@163.com
Received: August 23, 2020
Peer-review started: August 23, 2020
First decision: October 18, 2020
Revised: October 20, 2020
Accepted: November 4, 2020
Article in press: November 4, 2020
Published online: December 26, 2020
Processing time: 118 Days and 0.7 Hours
Abstract
BACKGROUND

Conventional clinical guidelines recommend that at least 12 lymph nodes should be removed during radical rectal cancer surgery to achieve accurate staging. The current application of neoadjuvant therapy has changed the number of lymph node dissection.

AIM

To investigate factors affecting the number of lymph nodes dissected after neoadjuvant chemoradiotherapy in locally advanced rectal cancer and to evaluate the relationship of the total number of retrieved lymph nodes (TLN) with disease-free survival (DFS) and overall survival (OS).

METHODS

A total of 231 patients with locally advanced rectal cancer from 2015 to 2017 were included in this study. According to the American Joint Committee on Cancer (AJCC)/Union for International Cancer Control (UICC) tumor-node-metastasis (TNM) classification system and the NCCN guidelines for rectal cancer, the patients were divided into two groups: group A (TLN ≥ 12, n = 177) and group B (TLN < 12, n = 54). Factors influencing lymph node retrieval were analyzed by univariate and binary logistic regression analysis. DFS and OS were evaluated by Kaplan-Meier curves and Cox regression models.

RESULTS

The median number of lymph nodes dissected was 18 (range, 12-45) in group A and 8 (range, 2-11) in group B. The lymph node ratio (number of positive lymph nodes/total number of lymph nodes) (P = 0.039) and the interval between neoadjuvant therapy and radical surgery (P = 0.002) were independent factors of the TLN. However,TLN was not associated with sex, age, ASA score, clinical T or N stage, pathological T stage, tumor response grade (Dworak), downstaging, pathological complete response, radiotherapy dose, preoperative concurrent chemotherapy regimen, tumor distance from anal verge, multivisceral resection, preoperative carcinoembryonic antigen level, perineural invasion, intravascular tumor embolus or degree of differentiation. The pathological T stage (P < 0.001) and TLN (P < 0.001) were independent factors of DFS, and pathological T stage (P = 0.011) and perineural invasion (P = 0.002) were independent factors of OS. In addition, the risk of distant recurrence was greater for TLN < 12 (P = 0.009).

CONCLUSION

A shorter interval to surgery after neoadjuvant chemoradiotherapy for rectal cancer under indications may cause increased number of lymph nodes harvested. Tumor shrinkage and more extensive lymph node retrieval may lead to a more favorable prognosis.

Keywords: Lymph node retrieval; Survival analysis; Neoadjuvant therapy; Rectal cancer; Tumor-node-metastasis stage; Prognosis

Core Tip: The number of lymph node retrieval and survival on surgery after neoadjuvant therapy in rectal cancer are still under debate. This study analyzes the effects of lymph node retrieval in rectal cancer after neoadjuvant therapy on patient survival. We concluded that a shorter interval to surgery after neoadjuvant chemoradiotherapy for rectal cancer under indications caused increased number of lymph nodes harvested. Tumor shrinkage and more extensive lymph node retrieval may lead to a more favorable prognosis.