Table 6.

Characteristics of the studies evaluating fish intake, n-3 LC-PUFA intake and fish oil supplements and cancers

Author	Outcomes	Type of study	Exposure	Results	Conclusion
Wu et al., 2012 Am J Med.	Colorectal cancer	MA 22 prospective cohort studies (N = 1,209,489 participants in total with 7,483 cases) and 19 case-control studies	Fish consumption, highest versus lowest	Fish consumption decreased the risk of colorectal cancer by 12% (summary OR, 0.88; 95% CI, 0.80–0.95). The pooled ORs of colorectal cancer for the highest versus lowest fish consumption in case-control studies and cohort studies were 0.83 (95% CI, 0.72–0.95) and 0.93 (95% CI, 0.86–1.01), respectively.	Findings suggest that fish consumption is inversely associated with colorectal cancer.
Vieira et al., 2017 Ann Oncol	Colorectal cancer	MA & SR 11 studies included in the dose-response meta-analysis 10,356 cases	Fish consumption, highest versus lowest	An increase of 100 g/day of fish was associated with lower risk of colorectal cancer, RR 0.89(95% CI 0.80–0.99)	The inverse association for fish intake showed low credibility because the results were mainly driven by one study in the analysis (40% weight).
Schwingshackl et al., 2018 Int. J. Cancer	Colorectal cancer	MA & SR 21 studies examined (cohort studies, case–cohort studies, follow-up of RCTs and nested case–control studies) 19,996 cases	Fish consumption, highest versus lowest	Overall risk estimates of 0.95 (0.87 to 1.03) per 100 grams fish per day There was no evidence of a nonlinear dose-response (15 studies included)	No statistically significant association was observed between fish intake and risk of colorectal cancer. However, an inverse association was observed for studies conducted in Europe, for long-term studies, and studies with 1,000 cases or more.
Lovegrove et al., 2015 Int J Clin Pract	Prostate cancer	SR 37 studies in total (case-control and cohort) 31 on PCa risk 8 on aggressiveness 3 on mortality 495,321 participants in total	Fish intake Fish oil intake	Overall, 10 studies considering PC-risk found significant inverse trends with fish and fish-oil intake. Three studies investigating fish consumption and PC-mortality identified a significantly reduced risk. Multivariate-OR (95% CI) were 0.9 (0.6–1.7), 0.12 (0.05–0.32) and 0.52 (0.30–0.91) at highest fish intakes.	Total fish and fish oil intake was not associated with prostate cancer risk but may be implicated in lower mortality risk.
Aucoin et al., 2017 Integrative Cancer Therapies	Prostate cancer	SR 11 cohort studies on primary prevention (17 publications) 13 publications on diet, one on supplement and 3 on both	Fish intake Fish oil	Of the analyses assessing prostate cancer incidence prospective, 12 did not show a statistically significant association. Five analyses showed a significant association between increased intake of fish-derived omega-3 fatty acids and decreased prostate cancer incidence.	Insufficient evidence to suggest a relationship between fish-derived omega-3 fatty acid and risk of prostate cancer. An association between higher omega-3 intake and decreased prostate cancer mortality may be present, but more research is needed
Zheng et al., 2013 BMJ	Breast cancer	MA & SR 21 cohort studies 11 studies on fish intake 687,770 participants 13,323 cases 17 studies on marine n-3 PUFA 527,392 participants 16,178	Fish intake n-3 LC-PUFA from diet or as tissue biomarker	High fish intake yielded overall risk estimate of 1.03 (0.93–1.14) High intake of n-3 LC-PUFA from diet yielded overall risk estimate of 0.86 (0.78–0.94)	High intake of n-3 LC-PUFA is associated with 14% reduction in risk of breast cancer
Wu et al., 2016 Nutrients	Breast cancer	MA 18 cohort studies 914,451 participants 19,400 cases	Fish intake (highest vs. Lowest and dose-response)	The summary RR for highest versus lowest was 1.04 (95% CI 0.97 to 1.12) Dose-response analysis showed that the summary RR per 120 g/day was 1.07 (95% CI 0.94 to 1.21)	A null association was observed for fish intake and risk of breast cancer.
Kazemi et al., 2021 Adv Nutr	Breast cancer	SR and MA Included were cohort, case-cohort, nested casecontrol studies, and follow-up studies of randomized controlled trials 17 studies 28,818 cases	Fish intake (dose-response)	Dose-response analysis showed that the summary RR per 100 g/day increase was 1.0 (95% CI 0.93 to 1.08)	A null association was observed for fish intake and risk of breast cancer.

^*Selection of topics for systematic reviews for the NNR2022 project

RR, Relative risk/Risk ratio; PUFA, polyunsaturated fatty acids; PCa, prostate cancer; SR, systematic review; MA, meta-analysis; RCT, randomized controlled trial; OR, Odds ratio; RR, Relative risk/Risk ratio.