Ethics approval and consent to participate
This study was approved by the Ethics Committee of The First Hospital of Lanzhou University (approval number: LDYYLL2012001). All subjects provided written informed consent.
Consent for publication
Not applicable
Availability of data and materials
The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.
Competing interests
The authors declare that they have no potential competing interests (financial, professional, or personal) relevant to the manuscript.
Funding
The research reported was supported by the Ministry of Science and Technology of the People’s Republic of China [2012GS620101]. The role of the funding body in the design of the study and collection, analysis, and interpretation of data and in writing the manuscript.
Authors’ contributions
XZ majorly contributed in the design and performance of the study, the analysis of data, and the writing of the manuscript.
ZC equally contributed to the investigation, the operation and the supervision of the project of the Wuwei cohort, the collection of data, and the endoscopic examination for subjects.
QG equally contributed to the investigation, the operation, and the supervision of the project of the Wuwei cohort, the collection of data, and the endoscopic examination for subjects.
YW equally contributed in the investigation and administration of the project of Wuwei cohort, and the collection and the collation of data.
ZZ equally contributed in the investigation and administration of project of Wuwei cohort, and the collection and the collation of data.
RJ equally contributed in the investigation of project of Wuwei cohort, the collection of data, and the endoscopic examination for subjects.
YZ equally contributed in the curation, analysis, and validation of data.
JZ equally contributed in the endoscopic examination for subjects the collection of data.
ZW equally contributed in the endoscopic examination for subjects the collection of data.
ML equally contributed in the pathological analysis of biopsy samples.
XW equally contributed in the endoscopic examination for subjects and the collection of data.
YY equally contributed in the endoscopic examination for subjects and the collection of data.
XL equally contributed in the endoscopic examination for subjects and the collection of data.
FA equally contributed in the endoscopic examination for subjects and the collection of data.
CX equally contributed in the endoscopic examination for subjects and the collection of data.
LL equally contributed in the endoscopic examination for subjects and the collection of data.
PF equally contributed in the endoscopic examination for subjects and the collection of data.
JZ equally contributed in the endoscopic examination for subjects and the collection of data.
QG equally contributed in the endoscopic examination for subjects and the collection of data.
QL equally contributed in the endoscopic examination for subjects and the collection of data.
ML equally contributed in the endoscopic examination for subjects and the collection of data.
QR equally contributed in the endoscopic examination for subjects and the collection of data.
XH equally contributed feasibility analysis of the project of Wuwei cohort and the formulation of the cluster sampling method.
HL equally contributed in the endoscopic examination for subjects and the collection of data.
YW equally contributed in the endoscopic examination for subjects and the collection of data.
HZ equally contributed in the endoscopic examination for subjects and the collection of data.
YZ equally contributed in the endoscopic examination for subjects and the collection of data.
XG equally contributed in the endoscopic examination for subjects and the collection of data.
XS equally contributed in the endoscopic examination for subjects and the collection of data.
JW equally contributed in the endoscopic examination for subjects and the collection of data.
ZH equally contributed in the endoscopic examination for subjects and the collection of data.
RL equally contributed in the collection and the collation of data.
HY equally contributed in the collection and the collation of data.
JL equally contributed in the curation, analysis, and validation of data.
LQ equally contributed in the feasibility analysis of the project of Wuwei cohort, the formulation of endoscopic operation procedures and pathological analysis methods.
YZ majorly contributed in the design, the operation, and the supervision of the project of Wuwei cohort; was responsible for the names and order of authors, the verification of all data, figures, materials, and the submission and all substantive correspondence with editors.
Acknowledgments
The authors are grateful to all study participants and staff from collaborating hospitals. We thank the interviewers from the CDC of Wuwei City and the Department of Epidemiology and Statistics, School of Public Health, Lanzhou University.
This work was supported by the Ministry of Science and Technology of the People’s Republic of China [2012GS620101].