title: Vitamin C Intake and Pancreatic Cancer Risk: A Meta-Analysis of Published Case-Control and Cohort Studies.
abstract: BACKGROUND
  Observational studies inconsistently reported the relationship between vitamin C intake and risk of pancreatic cancer. We conducted a meta-analysis of published case-control and cohort studies to quantify the association.
  
  
  METHODS
  Potentially eligible studies were found on PubMed and EMBASE databases through May 31, 2015. A random-effects model was assigned to compute summary point estimates with corresponding 95% confidence intervals (CIs). Subgroup and meta-regression analyses were also performed to explore sources of heterogeneity.
  
  
  RESULTS
  Our final analyses included 20 observational studies comprising nearly 5 thousand cases of pancreatic cancer. When comparing the highest with the lowest categories of vitamin C intake, the summary odds ratio/relative risk for case-control studies (14 studies), cohort studies (6 studies) and all studies combined was 0.58 (95% CI: 0.52-0.66), 0.93 (95% CI: 0.78-1.11) and 0.66 (95% CI: 0.58-0.75), respectively. The difference in the findings between case-control and cohort studies was statistically significant (P < .001). Possible publication bias was shown in the meta-analysis of case-control studies.
  
  
  CONCLUSIONS
  There is insufficient evidence to conclude any relationship between vitamin C intake and risk of pancreatic cancer. The strong inverse association observed in case-control studies may be affected by biases (eg, recall and selection biases) that particularly affect case-control studies and/or potential publication bias. Future prospective studies of vitamin C intake and pancreatic cancer are needed.
authors: Department of Hepatobiliary and Pancreatic Surgery, Ningbo Medical Treatment Center Lihuili Hospital, Ningbo, 315000, China.
authors: Yong-Fei
authors: YF
authors: Hua
authors: Department of Hepatobiliary and Pancreatic Surgery, Ningbo Medical Treatment Center Lihuili Hospital, Ningbo, 315000, China.
authors: Gao-Qing
authors: GQ
authors: Wang
authors: Department of Hepatobiliary and Pancreatic Surgery, Ningbo Medical Treatment Center Lihuili Hospital, Ningbo, 315000, China.
authors: Wei
authors: W
authors: Jiang
authors: Department of Hepatobiliary and Pancreatic Surgery, Ningbo Medical Treatment Center Lihuili Hospital, Ningbo, 315000, China.
authors: Jing
authors: J
authors: Huang
authors: Department of Nutrition and Food Hygiene, School of Public Health, Soochow University, Suzhou, 215123, China.
authors: Guo-Chong
authors: GC
authors: Chen
authors: Department of Hepatobiliary and Pancreatic Surgery, Ningbo Medical Treatment Center Lihuili Hospital, Ningbo, 315000, China.
authors: Cai-De
authors: CD
authors: Lu
mesh_terms: D000975:Antioxidants / Q000008:administration & dosage* / Q000627:therapeutic use; D001205:Ascorbic Acid / Q000008:administration & dosage* / Q000627:therapeutic use; D016022:Case-Control Studies; D015331:Cohort Studies; D006801:Humans; D010190:Pancreatic Neoplasms / Q000453:epidemiology* / Q000517:prevention & control; D012306:Risk
chemical_list: D000975:Antioxidants; D001205:Ascorbic Acid