Table 1. Baseline characteristics of studies included in the present meta-analysis.

Study	Year	Country/ region	Outcome	TNM stage	Treatment	Sample size	Cut-off value for Ki-67	Analysis of HR	Study design	Detection method	NOS score
Ben-Haj-Ayed	2016	Tunisia	OS, DFS	I–IV	Mixed	71	≥5%	Multivariate	Retrospective	IHC	7
Chang	2017	Taiwan	DFS, DMFS, LRFS	I–IV	Mixed	124	H-score ≥ median	Univariate	Retrospective	IHC	7
Fan	2019	China	DMFS	III–IV	Chemoradiotherapy	147	≥5%	Univariate	Prospective	IHC	8
Fountzilas	2012	Greece	OS, DFS	II–IV	Chemoradiotherapy	141	≥5%	Multivariate	Prospective	IHC	9
Genç	2000	Turkey	OS	I–IV	Radiotherapy	35	≥10%	Univariate	Retrospective	IHC	6
Guan	2015	China	OS, DFS	I–IV	Mixed	58	≥10%	Multivariate	Retrospective	IHC	7
Kijima	2001	Japan	OS	II–IV	Radiotherapy	19	≥50%	Univariate	Retrospective	IHC	6
Lu	2017	China	OS, DFS, DMFS, LRFS	I–IV	Chemoradiotherapy	334	≥10%	Univariate	Retrospective	IHC	8
Shi	2015	China	OS	I–IV	Chemoradiotherapy	55	≥50%	Univariate	Retrospective	IHC	7
You	2015	China	OS	I–IV	Mixed	118	≥50%	Univariate	Retrospective	IHC	7
Zhang	2016	China	OS	I–IV	Chemoradiotherapy	59	≥25%	Univariate	Retrospective	IHC	8
Zhao	2018	China	OS, DFS	I–IV	Mixed	45	≥77.5%	Multivariate	Retrospective	IHC	6
Zhao	2017	China	DFS	III–IV	Mixed	108	≥10%	Multivariate	Retrospective	IHC	8