Table 1. General characteristics of included studies.

Author	Year	Country	No. of Patients	Specimens	Test methods	Markers	Cut-off	Treg Positive Expression (%)	Stage	Pre-therapy	Outcomes
Liu et al.	2006	China	61	PB	FCM	CD4+ CD25+	< 3%	29.4	I–IV	Not applicable	Overall survival
Shimizu et al.	2010	Japan	100	Tumor tissues, RLN	IHC	Foxp3+	≥ 3 in 10 HPFs	51.0	I–III	Surgery	Recurrence-free survival
Erfani et al.	2012	Iran	23	PB	FCM	CD4+ CD25+ Foxp3+	Not applicable	Not applicable	II–IV	No prior treatment	Not applicable
Kayser et al.	2012	Germany	232	Tumor tissues	IHC	CD4+ CD25+	> median number	50.0	I–IV	Surgery	Overall survival
Tao et al.	2012	Japan	87	Tumor tissues	IHC	Foxp3+	≥ 25 in 10 HPFs	31.0	I–III	Surgery	Recurrence-free survival, overall survival
Hanagiri et al.	2013	Japan	158	PB, RLN	FCM	CD4+ CD25+ Foxp3+	> 0.5% of PBL, > 1.1% of RLNL	Not applicable	I–III	Surgery	Overall survival
Kinoshita et al.	2013	Japan	200	Tumor tissues	IHC	Foxp3+	≥ 6 in 1 HPFs	46.5	I	Surgery	Recurrence-free survival, overall survival
Hanagiri et al.	2014	Japan	131	Tumor tissues, PB, RLN	qRT-PCR	Foxp3+	2−△CT> 0.06	25.2	I	Surgery	Overall survival
He et al.	2015	China	50	PB	FCM	CD4+ CD25+	Not applicable	Not applicable	I–IV	No prior treatment	Overall survival
O’ Callaghan et al.	2015	Australia	197	Tumor tissues, RLN	IHC	Foxp3+	> median value*	43.9	I–IIIA	Surgery	Overall survival
Muto et al.	2015	Japan	64	Tumor tissues, PB	IHC, FCM	CD4+ Foxp3+ Helios-	> median number	50.0	I–IV	Surgery, chem therapy	Recurrence-free survival, overall survival

PB: peripheral blood; RLN: regional lymph nodes; FCM: flow cytometry; IHC: immunohistochemistry; HPFs: high-power fields; qRT-PCR: quantitative real time-polymerase chain reaction.

^*median value was defined as the ratio of corresponding tumour islet and stroma counts.