A dose-dependent relationship between pre-illness BMI and EA was observed for males (OR 4.3, 95% CI 2.3-7.9, P<0.0001) in the highest BMI quartile versus the lowest. Especially for the lower esophagus, an OR of 11.3 (95% CI 3.5-36.4, P<0.001) was observed and for the gastrochemical structure esophageal junction the OR was 3.4 (95% CI: 1.4-8.7, P<0.001). Mechanism It was proposed that an increased occurrence of GERD among individuals who are obese can lead to occurrence of Barrett’s esophagus and finally esophageal

adenocarcinoma, a likely mechanism explaining the association Inhibitors,research,lifescience,medical between abdominal adiposity and esophageal adenocarcinoma (9). However, the associations between BMI or adiposity and this tumor were seemingly independent of the symptoms of GERD in virtually

all studies with GERD data (4,24,31,35,37). These results indicate that obesity might have an independent carcinogenic role in occurrence of esophageal adenocarcinoma. Nevertheless, since the mechanisms underlying Inhibitors,research,lifescience,medical the association between obesity and esophageal adenocarcinoma are not fully established, further research into the potential role of GERD in the carcinogenic pathway is Inhibitors,research,lifescience,medical warranted. There are several molecular mechanisms that can contribute to the increased risk of cancer among obese individuals (21), but the reasons behind the robust and specific association between obesity and esophageal adenocarcinoma still remain to be clarified. Research into the mechanisms underlying this association, however, is emerging. The insulinlike growth factor (IGF) pathway, which is associated with obesity, plays an important role in regulating cell proliferation, differentiation, apoptosis, and transformation. Laboratory studies have shown that IGFs exert strong mitogenic and antiapoptotic actions on Inhibitors,research,lifescience,medical various cancer cells. The IGF pathway has been shown to be associated with increased risk for several common Inhibitors,research,lifescience,medical cancers including breast (38), prostate (39), lung (40) and colorectum (41), and may represent a mechanistic link between obesity

and esophageal adenocarcinoma. Recent studies have shown that polymorphisms in genes encoding proteins belonging to the IGF family could be markers of increased risk of esophageal adenocarcinoma found (36). In a case-control study of 431 wellcharacterized individuals in Canada, Kimberley Macdonald et al. analyzed the frequency of the 1013G>A polymorphism in the gene encoding the IGFI receptor in a series and showed that individuals who were obese and carried the 1013G>A variant had a higher risk of developing esophageal adenocarcinoma than those who carried the 1013G>G variant. Thus, this commonly occurring gene polymorphism might modulate the risk of esophageal adenocarcinoma in individuals who are obese, probably by altering the function of the IGFI receptor (42). The cytokines leptin and adiponectinsecrected by adipocytes are other factors that might contribute to the link between obesity and esophageal adenocarcinoma.