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Eur J Cancer Prev. 2018 May;27(3):197-204. doi: 10.1097/CEJ.0000000000000401.

Tobacco smoking and gastric cancer: meta-analyses of published data versus pooled analyses of individual participant data (StoP Project).

Author information

1
EPI Unit, Instituto de Saúde Pública, Universidade do Porto.
2
Department of Biomedical and Clinical Sciences.
3
Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy.
4
Department of Epidemiology, UCLA Fielding School of Public Health and Jonsson Comprehensive Cancer Center, Los Angeles, California.
5
Division of Molecular Medicine, Aichi Cancer Center Research Institute, Nagoya, Japan.
6
Harbin Medical University, Harbin.
7
School of Epidemiology, Public Health and Preventive Medicine, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada.
8
Medical Informatics Center, Peking University, Peking, China.
9
Molecular and Nutritional Epidemiology Unit, Cancer Research and Prevention Institute-Istituto per lo Studio e la Prevenzione Oncologica (ISPO), Florence.
10
The Tisch Cancer Institute, Mount Sinai School of Medicine.
11
Digestive Oncology Research Center, Digestive Disease Research Institute, Tehran University of Medical Sciences, Tehran, Iran.
12
Department of Medical Epidemiology and Biostatistics.
13
Department of Epidemiology and Prevention, Russian N.N. Blokhin Cancer Research Center, Moscow, Russia.
14
Environmental and Cancer Epidemiology Unit, National Center of Epidemiology, Instituto de Salud Carlos III.
15
Consortium for Biomedical Research in Epidemiology and Public Health (CIBERESP).
16
Cancer Epidemiology Research Group, Oncology and Hematology Area, Health Research Institute Puerta de Hierro (IIS Puerta de Hierro), Madrid, Spain.
17
ISGlobal, Centre for Research in Environmental Epidemiology (CREAL).
18
IMIM (Hospital del Mar Medical Research Institute).
19
Universitat Pompeu Fabra (UPF), Barcelona.
20
Miguel Hernandez University and ISABIAL-FISABIO Foundation, Campus San Juan, Alicante, Spain.
21
Department of Agricultural, Food and Nutritional Sciences, University of Alberta, Edmonton, Alberta, Canada.
22
Nutritional Epidemiology Group, Centre for Epidemiology and Biostatistics, University of Leeds, Leeds.
23
Department of Community Medicine, Ardabil University of Medical Sciences, Ardabil, Iran.
24
Unit of Nutritional Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
25
Department of Social and Preventive Medicine, School of Public Health and Health Professions, University at Buffalo, Buffalo, New York.
26
Section of Hygiene, Institute of Public Health, Università Cattolica del Sacro Cuore.
27
Department of Medicine, Memorial Sloan Kettering Cancer Centre, New York.
28
Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK.
29
Department of Public Health and Community Health, School of Health Professions, Athens Technological Educational Institute.
30
Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA.
31
Department of Hygiene, Epidemiology and Medical Statistics, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece.
32
IRCCS San Raffaele Pisana, Rome, Italy.
33
Departamento de Ciências da Saúde Pública e Forenses e Educação Médica, Faculdade de Medicina, Universidade do Porto, Alameda Professor Hernâni Monteiro, Porto, Portugal.

Abstract

Tobacco smoking is one of the main risk factors for gastric cancer, but the magnitude of the association estimated by conventional systematic reviews and meta-analyses might be inaccurate, due to heterogeneous reporting of data and publication bias. We aimed to quantify the combined impact of publication-related biases, and heterogeneity in data analysis or presentation, in the summary estimates obtained from conventional meta-analyses. We compared results from individual participant data pooled-analyses, including the studies in the Stomach Cancer Pooling (StoP) Project, with conventional meta-analyses carried out using only data available in previously published reports from the same studies. From the 23 studies in the StoP Project, 20 had published reports with information on smoking and gastric cancer, but only six had specific data for gastric cardia cancer and seven had data on the daily number of cigarettes smoked. Compared to the results obtained with the StoP database, conventional meta-analyses overvalued the relation between ever smoking (summary odds ratios ranging from 7% higher for all studies to 22% higher for the risk of gastric cardia cancer) and yielded less precise summary estimates (SE ≤2.4 times higher). Additionally, funnel plot asymmetry and corresponding hypotheses tests were suggestive of publication bias. Conventional meta-analyses and individual participant data pooled-analyses reached similar conclusions on the direction of the association between smoking and gastric cancer. However, published data tended to overestimate the magnitude of the effects, possibly due to publication biases and limited the analyses by different levels of exposure or cancer subtypes.

PMID:
29595756
DOI:
10.1097/CEJ.0000000000000401
[Indexed for MEDLINE]

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