Arachidonic acid and cancer risk: a systematic review of observational studies

Abstract

BackgroundAn n-6 essential fatty acid, arachidonic acid (ARA) is converted into prostaglandin E2, which is involved in tumour extension. However, it is unclear whether dietary ARA intake leads to cancer in humans. We thus systematically evaluated available observational studies on the relationship between ARA exposure and the risk of colorectal, skin, breast, prostate, lung, and stomach cancers.MethodsWe searched the PubMed database for articles published up to May 17, 2010. 126 potentially relevant articles from the initial search and 49,670 bibliographies were scrutinised to identify eligible publications by using predefined inclusion criteria. A comprehensive literature search yielded 52 eligible articles, and their reporting quality and methodological quality was assessed. Information on the strength of the association between ARA exposure and cancer risk, the dose-response relationship, and methodological limitations was collected and evaluated with respect to consistency and study design.ResultsFor colorectal, skin, breast, and prostate cancer, 17, 3, 18, and 16 studies, respectively, were identified. We could not obtain eligible reports for lung and stomach cancer. Studies used cohort (n = 4), nested case-control (n = 12), case-control (n = 26), and cross-sectional (n = 12) designs. The number of subjects (n = 15 - 88,795), ARA exposure assessment method (dietary intake or biomarker), cancer diagnosis and patient recruitment procedure (histological diagnosis, cancer registries, or self-reported information) varied among studies. The relationship between ARA exposure and colorectal cancer was inconsistent based on ARA exposure assessment methodology (dietary intake or biomarker). Conversely, there was no strong positive association or dose-response relationship for breast or prostate cancer. There were limited numbers of studies on skin cancer to draw any conclusions from the results.ConclusionsThe available epidemiologic evidence is weak because of the limited number of studies and their methodological limitations, but nonetheless, the results suggest that ARA exposure is not associated with increased breast and prostate cancer risk. Further evidence from well-designed observational studies is required to confirm or refute the association between ARA exposure and risk of cancer.

Evidence-Based Guideline of the German Nutrition Society: Fat Intake and Prevention of Selected Nutrition-Related Diseases

“…The NIH-AARP also showed no association between the intake of n-6 fatty acids and risk of prostate cancer [277] (LOE IIb). In the systematic review by Sakai et al [288] (LOE IIa) on arachidonic acid, both studies with intake data and studies measuring the blood concentration of arachidonic acid demonstrated no association with the risk of prostate cancer.…”

Surfactant Protein B Suppresses Lung Cancer Progression by Inhibiting Secretory Phospholipase A2 Activity and Arachidonic Acid Production

“…Once activated, cPLA 2 α can produce AAs and other lipid products responsible for activation of sPLA 2 , which forms a positive feedback loop. The increase in AA by crosstalk between sPLA 2 and cPLA 2 α plays an important role in promoting cancer progression [20]. In addition, AA can be utilized to produce prostaglandin E2, which induces cell proliferation, immune suppression, angiogenesis and cancer invasion [21].…”

Arachidonic acid intake and asthma risk in children and adults: a systematic review of observational studies

“…This is unavoidable, because there are more than ten meaningful fatty acids in foods or the human body. This reporting characteristic made it difficult to effectively search for observational studies with a focus on individual fatty acids such as ARA, which is similar to our previous review that evaluated the observational studies on the relationship between ARA exposure and cancer risk ( 35 ) . For example, six studies that were not identified due to ‘exposure’ could be included in the PubMed search by the addition of the search term ‘fatty’, but the initial number of articles from PubMed more than doubled.…”

“…To identify additional eligible publications, potentially relevant articles were searched from bibliographies of full-text articles that included descriptions of both ARA and asthma. Our previous review suggested that searches from bibliographies of articles including ARA were more efficient when enough articles were identified from the PubMed database ( 35 ) . They were screened using the same criteria as for the PubMed search.…”