High marine ω-3 polyunsaturated fatty acid (PUFA) intake may be associated with a lower risk of colorectal cancer with high-level, but not low-level, FOXP3+ T-cell density, according to a study published in JAMA Oncology.1

Researchers led by Mingyang Song, MD, ScD, of Harvard University in Boston, MA, conducted a prospective cohort study of 173 229 predominantly white participants who were enrolled in the Nurses’ Health Study (1984-2010) and Health Professionals Follow-up Study (1986-2010) in order to examine a link between marine ω-3 PUFA intake and colorectal cancer risk.

They measured the incidence of colorectal cancer characterized by CD3+, CD8+, CD45RO (PTPRC)+ or FOXP3+ T-cell densities in tumor tissue through immunohistochemical and computer-assisted image analysis.

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Among the observed participants, 125 172 of them with 2 895 704 person-years provided follow-up data about marine ω-3 PUFA intake every 4 years through a validated food frequency questionnaire. They were followed up for incident colorectal cancer evaluation.

Of 2504 cases of colorectal cancer, 614 were further identified from which the researchers could assess T-cell infiltration in the tumor microenvironment.

They found that the inverse association of marine ω-3 PUFAs intake with colorectal cancer risk differed according to FOXP3+ T-cell infiltration. Those with an intake of less than 0.35 g/d of marine ω-3 PUFAs were associated with a multivariable hazard ratio of 0.57 compared to those whose intake was 0.15 g/d. In contrast, the hazard ratio for FOXP3+ T-cell-low-tumors was found to be 1.14.

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They found no statistically significant differential association for high-density tumors according to CD3+, CD8+, or CD45RO+ cell density.

The authors noted that their findings suggest “a potential role of ω-3 PUFAs in cancer immunoprevention through modulation of regulatory T cells.”


  1. Song M, Nishihara R, Cao Y, et al. Marine ω-3 Polyunsaturated Fatty Acid Intake and Risk of Colorectal Cancer Characterized by Tumor-Infiltrating T Cells. [published online ahead of print May 5, 2016.] JAMA Oncol. doi:10.1001/jamaoncol.2016.0605.