Helicobacter pylori infection causes gastric cancer A? review of the epidemiological, meta-analytic, and experimental evidence

Table 1 IARC evaluation of schistosomes, liver flukes and H pylori

Agent (infectionwith)	Degree of evidence of carcinogenicity		Overall evaluation
	Human	Animal
Schistosoma haematobium	Sufficient	Limited	Definite carcinogen
Schistosoma japonicum	Limited	Limited	Possible carcinogen
Schistosoma mansoni	Inadequate	Limited	Not classifiable
Opisthorchis viverrini	Sufficient	Limited	Definite carcinogen
Opisthorchis felineus	Inadequate	Inadequate 1	Not classifiable
Clonorchis sinensis	Limited	Limited	Probable carcinogen 2
Helicobacter pylori	Sufficient	Inadequate 1	Definite carcinogen

¹ No data available.

² Other relevant data taken into account in making overall evaluation.

Table 2 Globocan 2002 incidence, mortality, and survival data for gastric cancer

	Incidence			Mortality			Prevalence
	n	CR	ASR	Deaths	CR	ASR	1-year	5-year
Males
World	603 419	19.3	22	446 052	14.3	16.3	302 067	951 403
Developed	195 782	33.7	22.3	128 721	22.2	14.5	117 377	409 777
Under-developed	405 211	15.9	21.5	315 603	12.4	17	184 690	541 626
Females
World	330 518	10.7	10.4	254 297	8.3	7.9	166 436	522 156
Developed	115 372	18.8	10	83 515	13.6	6.9	66 319	227 316
Under-developed	214 024	8.7	10.4	169 971	6.9	8.3	100 117	294 840

CR: Crude rate; ASR: Age standardized rate (World Standard).

Table 3 Summary of all meta-analyses looking at the association between H pylori and gastric cancer

StudyFactors	Huang et al 1998[16]	Danesh 1999[19]	Eslick et al 1999[18]	Xue et al 2001[93]	HCCG 2001[94]	Huang et al 2003[95]
Journal	Gastroenterology	Aliment Pharm Ther	Am J Gastroenterol	World J Gastroenterol	Gut	Gastroenterology
Number of studies	19	44	42	11	12	16
Cohort studies	5	10	8	0	0	0
Case-control studies	14	34	34	11	12	16
Peer-reviewed papers	18	37	42	†	12	12
Abstracts	1	7	0	†	0	4
Non-English language studies	English only	No restrictions	No restrictions	Chinese only	†	No restrictions
Searching method(s)	MEDLINE,	MEDLINE, Reference lists, hand searching	MEDLINE, Current contents, CINAHL, CANCER CD, Biological abstracts, manual searches, contact investigators	Chinese Biomedical database (CBM)	MEDLINE, contact investigators	MEDLINE, PubMed, contact investigators
	Conference proceedings (1994-1996), manual searches
Search terms used	Campylobacter pylori, stomach neoplasms, Helicobacter pylori	Campylobacter pylori, gastric adenocarcinoma, gastric cancer,	Campylobacter pyloridis, Campylobacter pylori, gastric carcinoma, gastric cancer, Helicobacter pylori	Helicobacter pylori, gastric carcinoma, gastric cancer, precancerous lesion of stomach	†	Helicobacter pylori, meta-analysis, stomach neoplasms
		Stomach cancer,
		Helicobacter pylori
Time period	1983-1996	1983-1998	1983-March 1999	1995-2001	1985-1999	1990-2003
H pylori status	Serology only	Serology only	Serology & histology	†	Serology	Serology
Statistical analysis	Random-effects M-H or D&L	Inverse-variance- weighted log risk odds	Random-effects D&L	Fixed-effects	Logistic regression	Random-effects D&L
Number of studies in analysis	19	10	42	11	12	16
Pooled oddas ratio (OR)	1.92	2.5	2.04	2.56	2.36	2.28
95% confidence interval (CI)	1.32-2.78	1.90-3.40	1.69-2.45	1.85-3.55	1.98-2.81	1.71-3.05
Overall (P-value) heterogeneity	0.2	> 0.05	0.001	> 0.05	0.09	< 0.001
Quality assessment	Yes	No	Yes	No	No	Yes
Assessment of publication bias	No	No	Yes	No	†	Yes
Duplicate studies	Removed	†	Removed	†	†	Removed
Number of reviewers	Two	One	Two	†	†	Three

† Not stated. D&L: DerSimonian & Laird ¹⁵. M-H: Mantel-Haenszel ¹⁶.