Table 1.

Main characteristics of all eligible studies in the meta-analysis.

Author/yr	Country	Sample size	Age (yr)	Location (colon/rectum)	Treatment	Follow-up (mo)	Cutoff value		High expression (%)	Outcome	Confounding variables	NOS score
Shibutani et al (2016) [11]	Japan	99	63 (27–86)	57/42	Chemotherapy	20.8 (2.6–73.2)	0.183		36 (36.4)	OS	Gender, age, tumor location, histological type, peritoneal dissemination, no. of metastasis, CEA, molecular targeted therapy, mGPS, NLR	7
Ni et al (2016) [12]	China	148	60.2 (20–74)	104/44	Chemotherapy	12 (0.4–67)	0.6712		45 (30.4)	OS	Sex, age, tumor location, neutrophils, platelets, lymphocytes, monocytes, globulin, hemoglobin, CRP	6
Solaini et al (2016) [13]	UK	194	66 (59–73)	113/81	Surgery	27 (IQR 10–42)	0.133		NA	OS	Age, CRP, albumin, GPS	7
Haruki et al (2017) [14]	Japan	106	64.5 (39–87)	NA	Mixed	Up to 120	0.04		59 (55.7)	OS/DFS	No. of lymph node metastases, tumor number and size, CEA, mGPS, neoadjuvant chemotherapy	8
Shibutani et al (2019) [15]	Japan	40	47.5% cases > 68	40/0	Chemotherapy	Up to 36	0.122		19 (47.5)	OS/PFS	Gender, age, tumor location, no. of metastasis, RAS status, PS, no. of prior regimens, LDH, combined targeted therapy	6
Sakamoto et al (2020) [16]	Japan	184	63.1 (25–94)	184/0	Mixed	Up to 41	0.093		33 (17.9)	OS/RFS	Gender, age, tumor location, tumor number, and size, CEA, CA19–9	8

CA19–9 = carbohydrate antigen 19–9, CEA = carcinoembryonic antigen, CRP = C-reactive protein, DFS = disease-free survival, GPS = Glasgow Prognostic Score, IQR = interquartile range, LDH = lactate dehydrogenase, mGPS = modified Glasgow Prognostic Score, NLR = neutrophil-lymphocyte ratio, NA = not available, NOS = Newcastle–Ottawa Quality Assessment Scale, OS = overall survival, PFS = progression-free survival, PS = performance status, RAS status = RAS type GTPase family status, RFS = recurrence-free survival.