Association between alcohol consumption and pancreatic cancer: a systematic review of cohort studies

Background: Among all types of cancers, pancreatic cancer has poor prognosis with 5- year survival below 10%. In theory, alcohol intake may be a modifiable risk factor for pancreatic cancer due to its role in multiple carcinogenic and metabolic signaling pathways. In addition, alcohol consumption may lead to chronic pancreatitis which is underlying cause of pancreatic cancer. However, little is known about whether this factor is associated with pancreatic cancer. This study aimed to systematically review the cohort studies investigating the possible link between alcohol consumption and the morbidity or mortality of pancreatic cancer. Methods: This study was carried out based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). All of cohort studies that assessed the association between alcohol intake and the risk of pancreatic cancer or death were included in this systematic review without a language restriction. Electronic databases including PubMed, Web of science, Scopus, and Google scholar were searched using the keywords "pancreatic cancer" and "alcohol" and similar words from 1990 to April 2021 to find the cohort studies. Results: 858 articles were identified, of which 806 were excluded and the full-text of 52 papers were evaluated for the eligibility. Eventually, 22 articles were eligible and were included in this study. Many of the articles assessed the impacts of low to moderate alcohol intake. A comprehensive review of these studies showed that low to moderate alcohol consumption had a non-significant correlation with pancreatic cancer, while high alcohol consumption was significantly associated with the risk of pancreatic cancer or death. The results also revealed that high liquor consumption was associated with higher risk of pancreatic cancer. Nevertheless, the follow-up durations in most of these studies were shorter than that to lead to pancreatic cancer. Conclusion: Long-term heavy alcohol drinking can increase the morbidity or mortality of pancreatic cancer. Regarding that several genetic and environmental variations involve in the pathogenesis of this cancer, simultaneous control of these differences should be addressed to determine the net effect of alcohol drinking on pancreatic cancer.