Retrospective Cohort Study
Copyright ©The Author(s) 2021. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Hepatol. Jan 27, 2022; 14(1): 209-223
Published online Jan 27, 2022. doi: 10.4254/wjh.v14.i1.209
Prognostic factors of survival and a new scoring system for liver resection of colorectal liver metastasis
Kai-Chi Cheng, Ada Sze-Man Yip
Kai-Chi Cheng, Ada Sze-Man Yip, Department of Surgery, Kwong Wah Hospital, Hong Kong, China
Author contributions: Cheng KC designed the research study; Cheng KC and Yip ASM performed the research; Yip ASM analyzed the data and wrote the manuscript; all authors have read and approved the final manuscript.
Institutional review board statement: The protocol was approved by the Research Ethics Committee (Kowloon Central/Kowloon East) (Ref: KC/KC-21-0103/ER-1) in accordance with the laws and regulations (including Hong Kong laws), Hospital Authority policy, professional code of conduct, guidance of ICH GCP, and Declaration of Helsinki.
Informed consent statement: This study protocol was reviewed and approved by Hospital Authority Clinical Research Ethics Review Committee, reference number KCC/KEC-2021-0097. Written consent was not required as this is a retrospective study, and all data were retrospective. There was no prospective component to this study (i.e. patients were all anonymized, and there was no prospective follow-up). No patient was contacted for this study. All data were fully anonymized so that they cannot be traced back to an individual in this study.
Conflict-of-interest statement: The authors have no conflicts of interest to declare.
Data sharing statement: The datasets generated during and/or analyzed during the current study are not publicly available due to the potential that individual privacy could be compromised, but they are available in an anonymized form from the corresponding author upon reasonable request.
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: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Kai-Chi Cheng, FRCS (Ed), Doctor, Department of Surgery, Kwong Wah Hospital, No. 25 Waterloo Road, Kowloon, Hong Kong, China. thomascheng@hotmail.com
Received: October 7, 2021
Peer-review started: October 7, 2021
First decision: December 2, 2021
Revised: December 3, 2021
Accepted: December 23, 2021
Article in press: December 23, 2021
Published online: January 27, 2022
Processing time: 105 Days and 19.8 Hours
ARTICLE HIGHLIGHTS
Research background

Colorectal cancer is the third leading cause of cancer-related death in developed countries. About half of the cases will develop liver metastasis. Hepatic resection has become the standard management in selected patients, with a reported 5-year survival rate ranging from 36% to 60% after curative liver resection.

Research motivation

Patients with colorectal liver metastasis (CLM) are a heterogeneous group, with variable prognoses even after liver resection. As such, many studies have investigated factors that might influence the recurrence and survival of this group of patients, with a hope to differentiate patients that would best benefit from surgical resection from those who should be directed to palliative care.

Research objectives

The objectives of the present study were to identify the prognostic factors of survival in patients subjected to resection of CLM and to propose a risk score accordingly, to differentiate these patients.

Research methods

Between June 1999 and June 2020, all resections of CLM at Kwong Wah Hospital were recorded prospectively in the institution’s database and retrospectively analyzed. Variables affecting long-term survival were determined using the Cox proportional hazards regression model. A clinical risk score for overall survival was formulated according to factors identified by multivariate analysis.

Research results

On multivariate analysis, the number of liver metastases ≥ 5 [hazard ratio (HR): 2.962, 95% confidence interval (CI): 1.174-7.473, P = 0.022], the size of the largest liver lesion ≥ 4 cm (HR: 2.983, 95%CI: 1.343-6.625, P = 0.007), and the presence of nodal metastasis from the primary tumor (HR: 1.955, 95%CI: 1.031-3.707, P = 0.040) were associated with a worse overall survival. These three factors were chosen as criteria for a clinical risk score for overall survival, and the total risk score was compared with overall survival using the log-rank test. Lower total risk score groups had a significantly improved overall survival than the higher total risk score group.

Research conclusions

The newly proposed clinical risk score consisting of three significant prognostic factors (nodal metastasis from the primary tumor, number of liver metastases, and size of the largest liver tumor) is simple and easy to use. Priority over surgical resection should be given to the lowest score groups, and alternative oncological treatment should be considered in the group of patients with the highest score.

Research perspectives

Small study population (98 patients) and retrospective design limit the conclusions on associations over time. Future study with an expanded study population may allow weighting assignment to each component of the clinical risk score for a more accuracy in prognosis prediction. An external validation study is needed for the actual application of this clinical score in clinical use.