Relationship between Helicobacter pylori infection and programmed death-ligand 1 in gastric cancer: A meta-analysis

Table 1 Characteristics of the included studies, n (%)

Ref.	Design	Country	Diagnosis	Sample size	Mean age (years)	Men (%)	Stage	HP evaluation	HP positive	PD-L1 evaluation and cutoffs	PD-L1 expression
Koizumi et al[27], 2022	CS	Japan	Patients with GC after resection who underwent R0 gastrectomy	491	69	67.0	I-III	Immunohistochemistry	175 (35.6)	IHC (≥ 10%)	152 (30.9)
Shen et al[28], 2019	CS	China	Patients with early GC	54	65	46.3	I	Pathological evaluation or histological immunostaining	19 (35.2)	IHC (≥ 1%)	24 (44.4)
Yoshida et al[29], 2022	CS	Japan	Patients with GC or GEJC for total or partial	106	68	67	I-IV	Biopsy, serum test, or breath antibody test	53 (50.0)	CPS (≥ 1)	73 (68.9)
Böger et al[30], 2016	CS	Germany	Patients with GC or GEJC for total or partial gastrectomy	392	68	62.4	I-IV	Histological PCR	61 (15.9)	IHC (≥ 5%)	93 (23.7)
Che et al[18], 2022	CS	China	Patients with GC or GEJC	25	NA	70.1	III-IV	Histopathology, HpSA, or breath antibody test	14 (56.0)	NA	8 (32.0)
Magahis et al[31], 2023	CS	United States	Patients with stage IV GC	121	59	65.1	IV	Histopathology, serum test, or breath antibody test	25 (20.7)	CPS (≥ 1%)	76 (62.8)
Wu et al[32], 2017	CS	China	Patients with GC for total or partial gastrectomy	102	NA	74.7	I-IV	Serum test	62 (60.8)	IHC (≥ 5%)	62 (60.8)
Jia et al[17], 2024	CS	China	Patients with GC	562	NA	48.9	I-IV	Breath antibody test	290 (51.6)	CPS (≥ 1%)	331 (58.9)
Liu et al[33], 2020	CS	Korea	Patients with GC for gastrectomy	127	64	66.0	I-IV	Pathological evaluation or histological	55 (43.3)	CPS (≥ 1%)	74 (58.3)
Di Bartolomeo et al[34], 2015	CS	Italy	Patients with GC after resection	55	62	64	II-III	Pathological evaluation or histological immunostaining	23 (41.8)	IHC (≥ 5%)	37 (67.3)
Kuo et al[35], 2017	CS	Korea	Patients with GC after radical resection	112	NA	NA	I-IV	Histological PCR	43 (38.4)	IHC (≥ 5%)	35 (31.3)
Sughayer et al[36], 2020	CS	Jordan	Patients with GC for total or partial gastrectomy	92	63	61	I-IV	Pathological evaluation or histological immunostaining	10 (10.9)	CPS (≥ 1%)	63 (68.5)
Tseng et al[37], 2020	CS	China	Patients with GC after radical resection	370	NA	81	I-III	Histological PCR	97 (26.2)	CPS (≥ 1%)	78 (21.4)
Fang et al[38], 2020	CS	China	Patients with GC after radical resection	460	NA	71	I-III	Histological PCR	157 (34)	CPS (≥ 1%)	140 (30.0)

HP: Helicobacter pylori; PD-L1: Programmed death ligand-1; CS: Cross - sectional study; GC: Gastric cancer; IHC: Immunohistochemistry; GEJC: Gastroesophageal junction cancer; CPS: Combined positive score; PCR: Polymerase chain reaction; NA: Not available; HpSA: Helicobacter pylori stool antigen.

Table 2 The Newcastle-Ottawa scores of the included studies

Ref.	Adequate definition of cases	Representativeness of cases	Selection of controls	Definition of controls	Control for age and sex	Control for other confounders	Exposure ascertainment	Same methods for events ascertainment	Non-response rates	Total
Koizumi et al[27], 2022	1	1	1	1	0	0	1	1	1	7
Shen et al[28], 2019	1	1	1	1	0	0	1	1	1	7
Yoshida et al[29], 2022	1	1	1	1	0	0	1	1	0	6
Böger et al[30], 2016	1	1	1	1	0	0	1	1	1	7
Che et al[18], 2022	1	1	1	1	0	0	1	1	0	6
Magahis et al[31], 2023	1	1	1	1	0	0	1	1	0	6
Wu et al[32], 2017	1	1	1	1	0	0	1	1	0	6
Jia et al[17], 2024	1	1	1	1	0	0	1	1	1	7
Liu et al[33], 2020	1	1	1	1	0	0	1	1	0	6
Di Bartolomeo et al[34], 2015	1	1	1	1	0	0	1	1	1	7
Kuo et al[35], 2017	1	1	1	1	0	0	1	1	1	7
Sughayer et al[36], 2020	1	1	1	1	0	0	1	1	1	7
Tseng et al[37], 2020	1	1	1	1	0	0	1	1	1	7
Fang et al[38], 2020	1	1	1	1	0	0	1	1	1	7