Dietary Flavonols Intake and Risk of Esophageal and Gastric Cancer: A Meta-Analysis of Epidemiological Studies

Abstract

Background: Esophageal cancer (EC) and gastric cancer (GC) are common cancers and leading causes of cancer deaths worldwide. Many studies have investigated the association between dietary flavonols intake and the risk of EC and GC, but the results are inconsistent. Hence, we conducted a systematic analysis of relevant population-based studies to assess the association and derive a more precise estimation. Methods: The Cochrane, PubMed and Embase databases were searched to identify articles published through January 2016 that met the predetermined inclusion criterion. Twelve studies involving 4593 patients and 519,378 controls were included. Results: The summary odds ratios (ORs) of EC, GC and the two combined were respectively 0.88 (95% CI: 0.73–1.08), 0.80 (95% CI: 0.70–0.91) and 0.83 (95% CI: 0.74–0.92) for the highest category of dietary flavonols intake compared with the lowest. No significant heterogeneities were observed in these studies. Further analysis showed that the pooled ORs of EC and GC for cohort, population-based case-control and hospital-based case-control studies were 0.90 (95% CI: 0.61–1.34), 0.92 (95% CI: 0.72–1.18), 0.68 (95% CI: 0.38–1.24) and 0.83 (95% CI: 0.65–1.06), 0.84 (95% CI: 0.45–1.59), 0.70 (95% CI: 0.56–0.88). The subgroup analyses revealed a significant association of flavonol intake with a reduced risk of noncardia gastric adenocarcinoma but not gastric cardia adenocarcinoma. Moreover, significant inverse associations of flavonol intake with GC risk were observed in women but not in men, in smokers but not in nonsmokers, in European populations but not in American populations. Similarly, a significant inverse association of flavonols intake with EC risk was also observed in smokers but not in nonsmokers. Conclusion: High intake of dietary flavonols is significantly related to a reduced risk of GC, especially in women and smokers.

Flavonoids, Flavonoid Subclasses, and Esophageal Cancer Risk: A Meta-Analysis of Epidemiologic Studies

“…To date, meta-analyses have mainly focused on dietary flavonoids and breast cancer [ 29 ], lung cancer [ 30 ], and stomach and colorectal cancer [ 16 ]. The latest meta-analysis found no significant association between dietary flavonols intake and the risk of esophageal cancer in four studies [ 31 ]. The results of published epidemiological studies are controversial because most of the studies found no significant association between dietary flavonoid intake and esophageal cancer; whereas two studies showed that flavonoids were associated with had significant reductions in the risk of esophageal cancer [ 32 , 33 ].…”

Polyphenol Intake and Gastric Cancer Risk: Findings from the Stomach Cancer Pooling Project (StoP)

“…Another Swedish population-based case–control study including 505 GC cases reported an inverse association with the flavonol quercetin [ 41 ]. Likewise, a meta-analysis involving 4593 cases supported the evidence of an inverse association between flavonols and GC risk [ 42 ].…”

Evaluation of Haptoglobin Genotype and Some Risk Factors of Cancer in Patients with Early Stage Esophageal Cancer

“…Based on the results of our study, the consumption of salt, hot tea, soft drinks, Deli meats and saturated oil in the patients' group was significantly higher than that of the control group. Some studies have demonstrated that inappropriate nutritional behaviors such as high salt intake and hot drinks can be associated with the incidence of gastrointestinal cancers (Shivanna and Urooj, 2016;Xie et al, 2016). It has been shown that the consumption of highly concentrated salt can induce mucosal membrane damage, stimulate inflammatory responses and increase the proliferation of epithelial cells, and subsequently increase the probability of carcinogenic genetic mutations (Wang et al, 2009).…”