Fish consumption and risk of non-Hodgkin lymphoma: A meta-analysis of observational studies

Objectives: Whether a relationship between fish consumption and non-Hodgkin lymphoma (NHL) risk exists is an open issue. We carried out a meta-analysis to explore this association according to the published observational studies. Methods: We performed a search of databases in MEDLINE and EMBASE to identify relevant studies. We derived meta-analytic estimates using random-effects models, and assessed between-study heterogeneity using the Cochran's Q and I-2 statistics. Results: We identified a total of seven case-control and two prospective cohort studies, including 7696 subjects with NHL. The summary relative risks (SRRs) estimated for NHL were 0.80 (95% confidence intervals (CIs): 0.68-0.94) for those in the highest fish consumption category compared with those in the lowest consumption category. There was evidence of significant heterogeneity across studies (Q = 26.72, P-heterogeneity = 0.002, I-2 = 66.3%). Stratified analysis by study design indicated that a significant risk association between fish consumption and NHL was observed in case-control studies, but not in cohort studies. Based on the dose-response meta-analysis, the SRRs of NHL were 0.85 (95% CIs: 0.71-1.01) for three servings increased per week of fish consumed with evidence of significant heterogeneity (P-heterogeneity = 0.007, I-2 = 63.9%). Conclusions: Findings from our meta-analysis indicate that consumption of fish may be not related to NHL risk.