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- Kim, Tai Lim, et al.
(author)
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Tea Consumption and Risk of Cancer: An Umbrella Review and Meta-Analysis of Observational Studies
- 2020
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In: ADVANCES IN NUTRITION. - : OXFORD UNIV PRESS. - 2161-8313. ; 11:6, s. 1437-1452
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Research review (peer-reviewed)abstract
- Tea is one of the most widely consumed beverages, but its association with cancer risk remains controversial and unclear. We performed an umbrella review to clarify and determine the associations between tea consumption and various types of cancer by summarizing and recalculating the existing meta-analyses. Meta-analyses of observational studies reporting associations between tea consumption and cancer risk were searched on PubMed and Embase. Associations found to be statistically significant were further classified into levels of evidence (convincing, suggestive, or weak), based on P value, between-study heterogeneity, prediction intervals, and small study effects. Sixty-four observational studies (case-control or cohort) corresponding to 154 effect sizes on the incidence of 25 types of cancer were included. Forty-three (27.9%) results in 15 different types of cancer were statistically significant. When combining all studies on the same type of cancer, 19 results in 11 different types of cancer showed significant associations with lower risk of gastrointestinal tract organ cancer (oral, gastric, colorectal, biliary tract, and liver cancer), breast cancer, and gynecological cancer (endometrial and ovarian cancer) as well as leukemia, lung cancer, and thyroid cancer. Only the reduced risk of oral cancer in tea-consuming populations (OR = 0.62; 95% CI: 0.55, 0.72; P value < 10(-6)) was supported by convincing evidence. Suggestive evidence was found for 6 results on biliary tract, breast, endometrial, liver, and oral cancer.To summarize, tea consumption was shown to have protective effects on some types of cancer, particularly oral cancer. More well-designed prospective studies are needed with consideration of other factors that can cause biases.
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- Lee, Keum Hwa, et al.
(author)
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Consumption of Fish and omega-3 Fatty Acids and Cancer Risk: An Umbrella Review of Meta-Analyses of Observational Studies
- 2020
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In: ADVANCES IN NUTRITION. - : OXFORD UNIV PRESS. - 2161-8313 .- 2156-5376. ; 11:5, s. 1134-1149
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Research review (peer-reviewed)abstract
- Multiple studies have suggested that omega-3 fatty acid intake may have a protective effect on cancer risk; however, its true association with cancer risk remains controversial. We performed an umbrella review of meta-analyses to summarize and evaluate the evidence for the association between omega-3 fatty acid intake and cancer outcomes. We searched PubMed, Embase, and the Cochrane Database of Systematic Reviews from inception to December 1, 2018. We included meta-analyses of observational studies that examined associations between intake of fish or omega-3 fatty acid and cancer risk (gastrointestinal, liver, breast, gynecologic, prostate, brain, lung, and skin) and determined the level of evidence of associations. In addition, we appraised the quality of the evidence of significant meta-analyses by using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. We initially screened 598 articles, and 15 articles, including 57 meta-analyses, were eligible. Among 57 meta-analyses, 15 reported statistically significant results. We found that 12 meta-analyses showed weak evidence of an association between omega-3 fatty acid intake and risk of the following types of cancer: liver cancer (n = 4 of 6), breast cancer (n = 3 of 14), prostate cancer (n = 3 of 11), and brain tumor (n = 2 of 2). In the other 3 meta-analyses, studies of endometrial cancer and skin cancer, there were no assessable data for determining the evidence levels. No meta-analysis showed convincing, highly suggestive, or suggestive evidence of an association. In the sensitivity analysis of meta analyses by study design, we found weak associations between omega-3 fatty acid intake and breast cancer risk in cohort studies, but no statistically significant association in case-control studies. However, the opposite results were found in case of brain tumor risk. Although omega-3 fatty acids have been studied in several meta-analyses with regard to a wide range of cancer outcomes, only weak associations were identified in some cancer types, with several limitations. Considering the nonsignificant or weak evidence level, clinicians and researchers should cautiously interpret reported associations between omega-3 fatty acid consumption and cancer risks.
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- Park, Jae Hyon, et al.
(author)
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Genetic variations in MicroRNA genes and cancer risk: A field synopsis and meta-analysis
- 2020
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In: European Journal of Clinical Investigation. - : WILEY. - 0014-2972 .- 1365-2362. ; 50:4
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Research review (peer-reviewed)abstract
- Background Cancer risk has been associated with certain gene variations in microRNA (miRNA), but conflicting evidence warrants re-assessing of significant results in meta-analyses. We summarized published meta-analyses that assess the associations between miRNA polymorphism and cancers to show the validity of the findings. Method We searched PubMed and investigated the results of meta-analyses published through November 2018. We re-assessed the results based on false-positive report probability (FPRP) to test the noteworthiness of the associations. Results Sixty-eight miRNA polymorphisms in 45 meta-analyses associated with cancer were included. Four (7.4%) and sixteen (25.0%) single nucleotide polymorphisms (SNPs) were noteworthy (FPRP < 0.2) at a prior probability of 0.001 for interesting candidate genes and a statistical power to detect an odds ratio (OR) of 1.1 and 1.5, respectively. The four miRNA SNPs noteworthy at an OR of 1.1 were as follows: miR-146a/rs2910164 Cvs.G; miR-27a/rs895819 Cvs.T; miR-423/rs6505162 Cvs.A; and miR-605/rs2043556 Cvs.T. The 16 SNPs noteworthy at an OR of 1.5 include the four genotype comparisons at an OR of 1.1, and the additional 12 genotype comparisons were as follows: miR-196a2/rs11614913 Tvs.C; miR-27a/rs895819 GGvs.AA + AG; miR-196a2/rs11614913 C vs.T; miR-146a/rs2910164 Gvs.C; miR-196a2/rs11614913 Tvs.C; miR-146a/rs2910164 Cvs.G; miR-499/rs3746444 homozygous model; miR-146a/rs2910164 CCvs.GG + GC; miR-499/rs3746444 TCvs.TT; miR-499/rs3746444 GAvs.AA; miR-146a/rs2910164 CCvs.GG; and miR-499/rs3746444 Gvs.A. No association was noteworthy at a prior probability of 0.000001. Conclusion Out of 68 published associations of miRNA polymorphisms with cancer, sixteen have shown noteworthiness in our re-assessing meta-analysis. Our findings summarize the results of meta-analyses on the association of cancer with SNPs and underline the importance of interpreting results with caution.
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