Association between alcohol flushing syndrome and cancer: A systematic review and meta-analysis.

Alcohol flushing syndrome (AFS) is experienced by up to 46% of East Asians. This study aimed to review the risk of cancers in AFS patients, elucidate an exposure-response relationship, and understand risk associated with alcohol intake and cancer. An electronic database search of PubMed, Embase, Scopus and Cochrane Library was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines. Observational studies on AFS' effects and all cancers risk were included. Studies including patients with existing malignancy were excluded. Dichotomous variables were pooled using the Mantel-Haenszel method with a random effects model. Sensitivity and subgroup analyses were performed. PROSPERO (CRD42023392916) protocol was followed. A total of 18 articles were included in the final analysis with a total of 387,521 participants. AFS was associated with an increased risk of all cancers (odds ratio [OR] 1.19, 95% confidence interval [CI] 1.06-1.34), esophageal squamous cell carcinoma (OR 1.47, 95% CI 1.05-2.05) and gastric adenocarci-noma (OR 1.40, 95% CI 1.14-1.72). Men with AFS exhibited an increased risk of all cancers (OR 1.34, 95% CI 1.13-1.59). However, this was not observed in women. All cancers risk was associated with AFS in those who consumed drink (i.e. consumed alcohol) more than 200 g of pure ethanol/week (OR 1.68, 95% CI 1.20-2.37) but not those who consumed less than 200 g of pure ethanol/week (OR 1.27, 95% CI 0.90-1.79) or non-drinkers (OR 0.99, 95% CI 0.67-1.47). AFS is associated with an increased risk of all cancers, particularly esophageal squamous cell carcinoma and gastric adenocarcinoma.