N-3 polyunsaturated fatty acids intake and risk of colorectal cancer: meta-analysis of prospective studies

• Published in: Cancer causes & control 2015-01, Vol.26 (1), p.133-141
• Main Authors: Chen, Guo-Chong, Qin, Li-Qiang, Lu, Da-Bing, Han, Tie-Mei, Zheng, Yan, Xu, Guo-Zhang, Wang, Xiao-Huai
• Format: Article
• Language: English
• Subjects: Bibliographic literature; Biomedical and Life Sciences; Biomedicine; Cancer Research; Colorectal cancer; Colorectal Neoplasms - epidemiology; Colorectal Neoplasms - etiology; Colorectal Neoplasms - prevention & control; Dietary Fats - administration & dosage; Epidemiology; Fatty acids; Fatty Acids, Omega-3 - administration & dosage; Female; Gender differences; Hematology; Humans; Male; Meta-analysis; Oncology; Original Paper; Prevention; Prospective Studies; Public Health; Risk Factors; Signal transduction
• ISSN: 0957-5243; 1573-7225
• DOI: 10.1007/s10552-014-0492-1

Background: Growing body of laboratory evidence supports the beneficial effects of n-3 polyunsaturated fatty acids (PUFAs) on colorectal cancer (CRC) prevention. Epidemiologic studies investigating the relationship between n-3 PUFAs intake and risk of CRC, however, have been inconsistent. We aimed to clarify the relation by conducting a meta-analysis of prospective studies. Methods: Eligible studies were identified by searching PubMed database and by carefully reviewing bibliographies of retrieved publications. Summary relative risks (RRs) with their 95 % confidence intervals (CIs) were computed with a random-effects model. Subgroup, metaregression, and dose–response analyses were performed to explore potential sources of heterogeneity. Results: A total of 14 prospective studies involving 8,775 cancer cases were included in the final analysis. Overall, total n-3 or marine PUFAs intake was not associated with risk of CRC (RR 0.99 and 1.00). However, there was a trend toward reduced risk of proximal colon cancer (total n-3 PUFAs: RR 0.83, 95 % CI 0.66–1.05; marine PUFAs: RR 0.81, 95 % CI 0.59–1.10) and a significant increased risk of distal colon cancer (total n-3 PUFAs: RR 1.26, 95 % CI 1.06–1.50; marine PUFAs: RR 1.38, 95 % CI 1.11–1.71). Furthermore, marine PUFAs intake accessed longer before diagnosis was associated 21 % reduced risk of CRC (RR 0.79, 95 % CI 0.63–1.00). Conclusion: Overall, this meta-analysis finds no relation between n-3 PUFAs intake and risk of CRC. The observed subsite heterogeneity within colon cancer and the possible effect modification by latency time merit further studies.