Smoking and gastric cancer: systematic review and meta-analysis of cohort studies.

Objective: We conducted a systematic review of studies addressing the relation between cigarette smoking and gastric cancer to estimate the magnitude of the association for different levels of exposure and cancer locations.

Methods: Published cohort, case-cohort, and nested case-control studies were identified through PubMed, Scopus, and Web of Science searches, from inception to July 2007. Relative risk (RR) estimates referring to the comparison of two categories of exposure (e.