Socioeconomic position and incidence of gastric cancer: a systematic review and meta-analysis

Background Low socioeconomic position (SEP) has been associated with increased risks of morbidity and mortality from many diseases. We investigated the associations between gastric cancer incidence and education, occupation and income as indicators for SEP. Methods We searched the PubMed and EMBASE databases for studies on SEP and gastric cancer incidence published from 1966 through February 2013. We used a random-effect model to pool the risk estimates from the individual studies. The relative indexes of inequality (RIIs) with their 95% CIs were used as summary estimates. We stratified the analysis by SEP indicators, sex, country's income group, geographical area, level of adjustment for an established risk factor, publication year, study design, type of control and length of follow-up. Results Of 1549 citations, 36 studies met our inclusion criteria. We observed an increased risk of gastric cancer among the lowest SEP categories in education (RII=2.97; 95% CI 1.923 to 4.58), occupation (RII=4.33; 95% CI 2.57 to 7.29) and combined SEP (RII=2.64; 95% CI 1.05 to 6.63) compared with the highest SEP categories. Although the association between the incidence of gastric cancer and the level of income is evident, it did not reach a statistically significant level (RII=1.25; 95% CI 0.93 to 1.68). Conclusions We found that the risk of gastric cancer incidence is higher among low SEP groups.