Retrospective Study
Copyright ©The Author(s) 2022. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Clin Cases. Oct 26, 2022; 10(30): 10906-10920
Published online Oct 26, 2022. doi: 10.12998/wjcc.v10.i30.10906
Prognostic impact of number of examined lymph nodes on survival of patients with appendiceal neuroendocrine tumors
Rui Du, Jiang-Wei Xiao
Rui Du, Jiang-Wei Xiao, Department of Gastrointestinal Surgery, The First Affiliated Hospital of Chengdu Medical College, Chengdu 610500, Sichuan Province, China
Author contributions: Xiao JW conceived the study; Du R collected, performed, and analyzed the data, and wrote the paper; Xiao JW and Du R carried out the data statistical processing and revised the paper; and All authors reviewed the results and approved the final version of the manuscript.
Institutional review board statement: The study was approved by the ethics committee of the First Affiliated Hospital of Chengdu Medical College.
Informed consent statement: The requirement for informed consent was waived by the committee because of the retrospective nature of the study.
Conflict-of-interest statement: All authors report no relevant conflicts of interest for this article.
Data sharing statement: No additional data are available.
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: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Jiang-Wei Xiao, MD, PhD, Professor, Department of Gastrointestinal Surgery, The First Affiliated Hospital of Chengdu Medical College, No. 278 Baoguang Avenue, Xindu District, Chengdu 610500, Sichuan Province, China. xiaojiangwei2018@163.com
Received: March 19, 2022
Peer-review started: March 19, 2022
First decision: May 1, 2022
Revised: May 8, 2022
Accepted: August 1, 2022
Article in press: August 1, 2022
Published online: October 26, 2022
Abstract
BACKGROUND

The prognosis of patients with appendiceal neuroendocrine tumors (ANETs) is related to lymph node (LN) metastasis and other factors. However, it is unclear how the number of examined LNs (ELNs) impact on survival.

AIM

To determine the factors affecting the cancer-specific survival (CSS) of patients with ANET and to evaluate the impact of the number of ELNs on survival.

METHODS

A total of 4583 ANET patients were analyzed in the Surveillance, Epidemiology, and End Results database. Univariate survival analysis was used to identify factors related to survival and the optimal number of ELNs and lymph node ratio (LNR) were determined by the Kaplan–Meier method. The survival difference was determined by CSS.

RESULTS

Except for sex, the other factors, such as age, year, race, grade, histological type, stage, tumor size, ELNs, LNR, and surgery type, were associated with prognosis. The 3-, 5-, and 10-year CSS rates of ANET patients were 91.2%, 87.5, and 81.7%, respectively (median follow-up period of 31 mo and range of 0-499 mo). There was no survival difference between the two surgery types, namely, local resection and colectomy or greater, in both stratifications of tumor size ≥ 2 cm (P = 0.523) and < 2 cm (P = 0.068). In contrast to patients with a tumor size < 2 cm, those with a tumor size ≥ 2 cm were more likely to have LN metastasis (χ2 = 378.16, P < 0.001). The optimal number of ELNs was more than 11, 7, and 18 for all patients, node-negative patients, and node-positive patients, respectively. CSS rates of patients with a larger number of ELNs were significantly improved (≤ 10 vs ≥ 11, χ2 = 20.303, P < 0.001; ≤ 6 vs ≥ 7, χ2 = 11.569, P < 0.001; ≤ 17 vs ≥ 18, χ2 = 21.990, P < 0.001; respectively). ANET patients with an LNR value ≤ 0.16 were more likely to have better survival than those with values of 0.17-0.48 (χ2 = 48.243, P < 0.001) and 0.49-1 (χ2 = 168.485, P < 0.001).

CONCLUSION

ANET ≥ 2 cm are more likely to develop LN metastasis. At least 11 ELNs are required to better evaluate the prognosis. For patients with positive LN metastasis, 18 or more LNs need to be detected and lower LNR values (LNR ≤ 0.16) indicate a better survival prognosis.

Keywords: Appendiceal neoplasm, Neuroendocrine tumors, Carcinoid tumor, Lymph node dissection, Lymph node ratio, Survival analysis

Core Tip: This study aimed to explore factors that have an influence on survival of patients with appendiceal neuroendocrine tumors. We identified the optimal number of examined lymph nodes that could achieve the best survival for patients with appendiceal neuroendocrine tumors with different lymph node statuses. Furthermore, lymph node ratio takes both examined lymph nodes and positive lymph nodes into account. We also identified the optimal value of lymph node ratio that could achieve the best survival for node-positive patients.